1. The Upper Room of Mark in Jerusalem
Pastor David Jang emphasizes that in Acts chapter 1, the scene where Jesus appears to His disciples with many proofs after His resurrection and teaches them about the kingdom of God for forty days is extremely important in this moment of waiting for the outpouring of the Holy Spirit (Pentecost). He points out that Acts 1 essentially marks the beginning of the Holy Spirit's work and the formation of the church's foundation, so we must pay attention to what happens in Jerusalem and in the Upper Room of Mark.
According to Acts 1:3, Jesus, who had suffered, died, and risen again, showed Himself alive to the disciples "by many convincing proofs." For forty days, He spoke about the kingdom of God. This period was a critical time in which despair and unbelief disappeared from the disciples' hearts, and the lordship and power of Jesus-confirmed by the resurrection-firmly took root within them. Pastor David Jang has repeatedly underscored how precious these forty days were. Without Jesus' direct explanation of the core of "the kingdom of God" and the coming outpouring of the Holy Spirit, the disciples might have only understood the resurrection as a mere "miraculous event."
However, Jesus reorganized the disciples and commanded them, "Do not leave Jerusalem, but wait for the gift My Father promised, which you have heard Me speak about" (cf. Acts 1:4). As a result, the disciples returned to Jerusalem and gathered in the "Upper Room of Mark." This was a decisive choice to overcome any lingering fear within them. Returning to Jerusalem-filled with the atmosphere of terror and threats-and gathering there not only reminded them of their previous "failure" when they scattered at the time of Jesus' suffering, but also represented a declaration of faith not to retreat in the face of any future threat.
Reading about Jesus' arrest in the Gospels (especially Matthew 26, Mark 14, Luke 22, and John 18) reveals the vivid fear and confusion the disciples experienced. When the Roman soldiers and the temple guard came armed to arrest Jesus, the disciples fled. Even Peter denied Jesus three times. Yet, after Jesus' resurrection, the disciples became equipped with resurrection faith once again, and ultimately they returned to Jerusalem. Pastor David Jang finds in this a great demonstration of the power of resurrection faith. Those who had scattered and gone back to Galilee after the death of their Teacher now gathered in the heart of Jerusalem to pray. At the center of that gathering was the "Upper Room of Mark."
The Upper Room of Mark is already mentioned in the Gospels as an important site. Traditionally, it is often referred to as the place where Jesus shared the "Last Supper" with His disciples, and it holds symbolic significance as a "hidden space" that served as the springboard for the birth of the early church. In Acts 1:13-14, the disciples gathered there and devoted themselves to prayer. They were putting into practice Jesus' teaching to "watch and pray," and they waited with earnest hearts for Pentecost. Though the upper room may have provided some measure of safety from the persecution and hostile gazes of the religious leaders of the time, there was still a tense atmosphere-they never knew what might happen next. Pastor David Jang repeatedly emphasizes how crucial it is to cling to God and focus on the promise of the Holy Spirit in such a place of "fear and tension."
Resurrection faith does not simply fix our attention on the astonishing fact of "coming back to life from the dead," but rather leads to the conviction that "the power of God's kingdom truly comes upon us" through this event. Through Jesus' resurrection, the disciples confirmed that He really was the Son of God, and that His words were neither false nor in vain. At the same time, they firmly grasped the promise that, even after Jesus departed from them, He would send the "Helper, the Holy Spirit," who would guide the church with the same power and love. This is why they remained in Jerusalem, continuously praying in the Upper Room of Mark.
Pastor David Jang interprets this "Upper Room of Mark" as the "starting point of the church." Before the church fully emerged around Jerusalem, these 120 believers gathered in the small upper room, praying and waiting for the promised Holy Spirit-an anticipation that leads directly to the Pentecost event in Acts chapter 2. Christian history spread rapidly from that very Upper Room of Mark. Once the disciples-formerly fishermen and tax collectors of no renown-received the Holy Spirit, the fire of the gospel began to ignite people's hearts. Through Peter's preaching, 3,000 repented, and then 5,000 more converted (Acts 2:41, 4:4). This was the practical fulfillment of Jesus' instruction, "You are the salt of the earth and the light of the world" (Matthew 5:13-14).
Although the English title of the Book of Acts is "The Acts of the Apostles," Pastor David Jang frequently asserts that it should be viewed less as the "acts of the apostles" and more as the "manifestation and work of the Holy Spirit." The main driving force that starts and expands the church is not the apostles' power, but the power of the Holy Spirit sent by the risen Jesus. Therefore, as believers read Acts, they witness how God accomplishes what people cannot, and the very first place where that happens is "the Upper Room of Mark in Jerusalem."
Pastor David Jang insists that this perspective must be applied to the modern church as well. A church does not grow simply because it has a large building or abundant finances, nor does the fruit of saving souls appear just because church leaders possess worldly power or knowledge. What matters is that the "essence" be restored: "For it is with your heart that you believe and are justified, and it is with your mouth that you profess your faith and are saved" (Romans 10:10). We must truly believe in the death and resurrection of Jesus and earnestly seek the Holy Spirit's power. For the early church, that "essential" was safeguarded in the upper room.
This upper room was also the site of fear on the day Jesus was arrested, where the disciples betrayed Him, and a place that held their sense of failure as well as the anxiety that they could be arrested and punished again. Yet it was equally the place where they confirmed the testimonies of Jesus' resurrection to one another and made the faith-based decision, "Let us start again in Jerusalem." At the moment the Holy Spirit descended, the seclusion and fear of that upper room were completely overturned, transforming it into the dynamic forward base of a gospel movement that would shake the world. Thus, the upper room serves to remind us of the "origin of the church."
Pastor David Jang often states that modern churches must recover the "spirituality of the Upper Room." This spirituality refers to an attitude of "keeping watch, praying, and clinging to the Word." Symbolically considering Jerusalem and the Upper Room of Mark, we see that, despite the human fear that pervaded the place, it became "the starting point of opening the gates of heaven." Even today, believers who go through countless failures and frustrations in their personal lives or church communities can, by holding onto resurrection faith and praying fervently, witness the astonishing work of the Holy Spirit.
Furthermore, Pastor David Jang frequently emphasizes that one must understand together the "holy fear" represented by Jerusalem and the "free space of prayer" represented by the Mount of Olives (Olivet). The disciples prayed with Jesus at the Mount of Olives, and that is also where Jesus ascended into heaven. But the actual place where they gathered in complete unity for prayer was the upper room inside Jerusalem. In other words, when the weight of reality (Jerusalem) meets the faith that looks to God's promise (the Mount of Olives), resurrection faith can be concretely carried out in life. No matter how much grace one experiences at the Mount of Olives, ultimately one must return to Jerusalem to form a "practical prayer group" and a "united community." The Upper Room of Mark thus becomes an historical and spiritual model for how the church community should unite and with what heart we should seek the Holy Spirit.
Pastor David Jang also stresses that this flow of history is not a "one-time event" that ended in the past, but something that continues to repeat itself today. Every person can have their own "Upper Room of Mark." In the midst of trials and anxieties that arise in our churches and in our individual lives, the moment we refuse to run away and instead return to Jerusalem to pray and seek the Holy Spirit is precisely that "Upper Room" moment. The crucial point is to recognize deeply that the resurrection of Jesus is not merely a single event that happened once, but is the power that continues to give us life, renews the community, and carries on the vision of God's kingdom. Just as "the church began in the Upper Room of Mark in Jerusalem," so too does "the revival of my own faith begin in some form of 'upper room.'"
Resurrection is power, and the manifestation of the Holy Spirit is the core energy that moves the church. This is the conclusion Pastor David Jang repeatedly highlights. And we see a comprehensive view of this in Acts 1-the resurrection of Jesus, His forty days of teaching, the return to Jerusalem, the prayers in the Upper Room of Mark-all leading to the Pentecost outpouring of the Holy Spirit we read about in Acts 2. From that event sprang forth the astounding evangelization of the world. Thus, that beginning point, the Upper Room of Mark in Jerusalem, is not merely a building or a historical site, but remains an enduring spiritual symbol that today's church and believers must recover.
2. The Selection of Matthias
In Acts chapter 1, along with the image of the disciples gathering in prayer in the Upper Room of Mark, we also see how they fill the vacancy left by Judas Iscariot, one of the Twelve. The reason the disciples had to maintain the number at twelve was not just about matching a figure, but because it symbolically represented the twelve tribes of Israel and had spiritual significance as part of God's structure. The betrayal of Judas Iscariot was an indelible wound and tragedy for both Jesus and the disciples. However, even this betrayal had been foretold, and was incorporated into God's plan of salvation and the fulfillment of the Scriptures (cf. Acts 1:16-20). Nevertheless, the disciples realized that filling that "missing seat" was absolutely necessary for carrying on the mission of the church.
The method the disciples used is intriguing. In Acts 1:21-22, Peter states that the person chosen must have been with them from the time of John's baptism until the day Jesus was taken up into heaven, so that he could testify to the resurrection of the Lord. Being appointed as an apostle was not merely about conveying Jesus' "teachings," but about personally witnessing "the life, death, and resurrection of Jesus," boldly proclaiming it, and spreading the gospel. Peter's criterion that the new apostle must be able "to be a witness of His resurrection" means that the person had to be utterly convinced to proclaim, "The Lord has risen" in the face of Jerusalem's fearful atmosphere and the world's scorn and persecution.
Before truly grasping the resurrection, the disciples were broadly split into two groups. One group became dejected-"Jesus is dead, so it's all over"-and returned to fishing (John 21). Another group, though smaller, held onto a sliver of hope, wondering if "the Lord might come back to life." But once Jesus actually rose from the dead and appeared several times over forty days, teaching and eating with them, they were completely transformed. Pastor David Jang explains that the driving force behind these disciples' return to Jerusalem, even after they had run away in human despair and discouragement, was precisely "resurrection faith."
Yet Judas, one of the Twelve, lost his apostolic authority through betrayal and met a tragic end. Acts 1:18-19 refers to Judas's death. He sold Jesus for thirty pieces of silver, and his death stands as a "bitter event" where human evil is revealed even within God's plan. Pastor David Jang interprets these verses as highlighting the destructive consequences when "greed" and "political ambition" combine, as they did in Judas Iscariot. He likely expected Jesus to be a political Messiah who would liberate the Jewish people from Rome. Over time, he recognized that Jesus' message of "obedience and sacrifice" did not match his own desires, prompting his betrayal. Ultimately, that betrayal led to his spiritual destruction, and Matthias took his place.
With Matthias's selection, the apostolic community regained its number of twelve. It symbolized that the "gate of God's kingdom was now properly re-established." Pastor David Jang often uses the word "restoration" when speaking of this moment. After Jesus' resurrection, as the disciples gathered in Jerusalem and prayed in the Upper Room, they filled the vacant spot so the church would have "an unshakable order" in anticipation of the Holy Spirit. Had they simply glossed over this issue, divisions might have emerged among the disciples after Jesus' ascension-perhaps disputes over "Who will be the leader?" or turmoil over Judas's betrayal and death. Yet through prayer and by adhering to the Scriptures, choosing "someone capable of bearing witness to the resurrection," the disciples resolved this matter with order and peace.
A noteworthy aspect of this process is the casting of lots. In the ancient Jewish tradition, casting lots was a method of seeking God's will in important decisions (Proverbs 16:33: "The lot is cast into the lap, but its every decision is from the Lord"). Pastor David Jang points out that, far from being a mere stroke of chance or probability, the casting of lots represented the faith of the community in God's absolute sovereignty. The two final candidates (Joseph called Barsabbas, also known as Justus, and Matthias) were both qualified. The final decision was entrusted to God's hands, and when they drew lots in prayer, Matthias was chosen. The disciples accepted that outcome and embraced Matthias as the new apostle. This serves as a "model of obedience" demonstrated by the early church, and shows the "core of order" in addressing potential conflicts or leadership appointments within the church.
Pastor David Jang goes on to say that Judas's place being filled by Matthias was essentially the first "corporate task" and "public decision" made by the apostolic community after Jesus' resurrection. In other words, resurrection faith does not end with each individual declaring, "I believe in Jesus' resurrection," but must be acted out within the church community: "We will clear away our failings and wounds, restore order and structure, and move forward together." Right after the disciples completed this process, Acts chapter 2's Pentecost event took place. This is no coincidence. The Holy Spirit sent by God does not fall powerfully on a place full of confusion and discord, but rather upon a repentant community that has established order through prayer and the Word. This is a lesson revealed in the historical account.
Some question why Matthias does not appear frequently thereafter in Acts. Pastor David Jang explains that the reason is not that his ministry was any less significant, but that Luke's writing primarily focuses on Paul, Peter, and the gospel's journey to Rome. Matthias, as one of the apostles, presumably carried out evangelistic work and contributed to the growth of the early church. However, since the narrative centers on Peter's travels and the journey of the gospel from Judea and Samaria to the Gentiles, eventually reaching Rome, it does not detail Matthias's individual ministry. Still, the record of his appointment and how he replaced Judas Iscariot is crucial in conveying the message that the early church was rebuilt both structurally and spiritually on resurrection faith.
Pastor David Jang often relates the process of choosing Matthias to the way contemporary churches appoint their leaders. When selecting church leaders (pastors, elders, missionaries, etc.), one must not simply look at their academic background, experience, or speaking skills. Instead, we need to ask, "Can this person truly bear witness to the resurrection of Jesus?" "Do they have unwavering conviction about the reality of the cross and the resurrection?" "Have they been living a life of continuous repentance and obedience to the Word?" The early church made those criteria clear: the person had to have witnessed Jesus' public ministry and be able to testify to His resurrection. Likewise, in the modern church, choosing a leader should be approached with deep prayer, seeking the Holy Spirit's guidance, and maintaining order and a posture of obedience.
Matthias's selection was a moment of recovery for the community, healing from the painful wound of Judas's betrayal. It was not merely about keeping the number twelve, but about the church officially standing up again. The disciples, having embraced the new era ushered in by Jesus' resurrection, gathered in the Upper Room of Mark to pray and wait for the Holy Spirit, and they recognized that "the apostolic circle had to be complete." Through the process of selecting Matthias, they were fully prepared to receive the Holy Spirit at Pentecost. Pastor David Jang sees in this an essential lesson for understanding the church: the church is not a mere gathering of people; each individual is called and established with their own unique backstory, which collectively forms God's grand design. No place is to be taken lightly. If someone falls away or fails, the church must pray and seek to fill that gap with the person God has chosen.
Hence, the account of Matthias in Acts 1 is also the story of how the early church overcame its internal wound and deficiency, reestablishing a new order based on resurrection faith. Pastor David Jang describes this as "the healing of the church community and the foundation for the coming of the Holy Spirit." Jesus spent forty days teaching after His resurrection, commanded the disciples to stay in Jerusalem until His ascension, and the disciples, gathered in one accord in the Upper Room of Mark, replaced Judas's empty place. All these elements were orchestrated flawlessly to usher in the new era of Pentecost in Acts chapter 2.
Pastor David Jang asserts that this sequence directly connects to Jesus' Great Commission to "preach the gospel to the ends of the earth." Jesus' parting mandate was, "Go into all the world and preach the gospel to all creation" (Mark 16:15). The Book of Acts records how that gospel was spread from Jerusalem all the way to Rome (Acts 28). Within this historical, redemptive movement, the Upper Room of Mark and the choosing of Matthias are crucial turning points. Had the disciples, discouraged by Judas's betrayal, scattered, or had they failed to restore the twelve-apostle structure and instead descended into internal discord and conflict, the remarkable spread of the gospel described in Acts might have faced significant obstacles.
Instead, they chose prayer over division and resurrection faith over despair, and they filled the vacant position by selecting Matthias. This became "the final preparatory stage" for receiving the Holy Spirit at Pentecost. Therefore, Acts chapter 1 vividly shows how the early church community came together and why the church must stand on "an order rooted in resurrection faith."
Pastor David Jang stresses that the same principle applies when we build churches or appoint leaders today. "Where does the essence of the church come from? It comes from faith in the resurrection and from the work of the Holy Spirit. In order to truly accept that work, we need the same obedience shown by the disciples who remained in Jerusalem to pray, in response to Jesus' command." From this vantage point, the choosing of Matthias was not a mere apostolic replacement, but the church community making a steadfast decision before God.
By extension, Pastor David Jang notes that as we study Scripture, we confirm through Acts 1 that "the kingdom of God cannot be destroyed." Even the severe crisis of Judas Iscariot's betrayal could not collapse the church. Within God's providence, it led to a new apostle being appointed, and the church was further solidified. This testifies to the fact that "the church stands on God's sovereignty and love, not on human merit or talent." Even today, when we witness regrettable events or discouraging situations in and outside of the church, we must find wisdom and courage in the early church's example. God's power can transform failure and betrayal into a process of refining the church, preparing it for the new age of the Holy Spirit.
Thus, the context of Acts 1 becomes clear. We have seen how the Upper Room of Mark in Jerusalem functioned as the cradle where the church first began, how the disciples gathered there through resurrection faith, and how the community restored the apostolic circle by "selecting Matthias," all leading toward the Pentecost outpouring in Acts chapter 2. Pastor David Jang repeatedly underscores that believers who "walk with the risen Jesus, yearn for the Holy Spirit's presence, and preserve order and obedience within their community" are able to see the church fulfill its original purpose of being light to the world and a channel for the gospel.
The Upper Room of Mark in Jerusalem was both the place where the early church concretely practiced resurrection faith and the community's birthplace in their expectation of the Holy Spirit. The selection of Matthias marked the healing of internal wounds and the process by which they readied themselves for Pentecost. All these truths remind us today that "resurrection faith is not confined to a personal confession, but reaches fuller maturity through communal order and decisive action." As Pastor David Jang frequently emphasizes, the Book of Acts itself is "the manifestation of the Holy Spirit" and shows how resurrection power was realized in history. And all of this began "in Jerusalem, in the Upper Room of Mark, and at the moment the Twelve-Apostle structure was restored by choosing Matthias."
In this way, Pastor David Jang reaffirms through the Upper Room of Mark in Jerusalem-where Jesus' resurrection faith began in action-and through the selection of Matthias to fill the void left by Judas Iscariot, that the church community reached a state of completion. This underscores again that the essence of the early church is a "church founded on the resurrection and the Holy Spirit." Even after two thousand years, this remains a timeless lesson, and Pastor David Jang persistently urges today's churches to hold fast to this essence.
