The Gospel's Chain Reaction: Gladness and Singleness of Heart Text: Acts 2:37-47
Introduction: The Birth of the Church Militant
We live in an age of manufactured realities and synthetic communities. People gather online around shared grievances or niche hobbies, and they call it fellowship. They rally for political causes, seeking a sense of belonging and purpose that has been hollowed out of their lives by a century of secularism. But what we see in Acts 2 is the genuine article. This is not a social club, a political action committee, or a support group. This is the explosive birth of the Christian Church, the visible manifestation of the Kingdom of God breaking into history. And it did not begin with a marketing plan or a focus group. It began with a sermon that cut men to the bone.
Peter has just finished preaching Christ crucified and risen. He has taken the central event of all human history, the resurrection, and laid it at the feet of the men who had, just weeks before, screamed for Jesus' blood. He did not soften the blow. He did not try to make the gospel palatable. He charged them directly: "let all the house of Israel therefore know for certain that God has made him both Lord and Christ, this Jesus whom you crucified." This is not seeker-sensitive language. This is a divine indictment. And the response was not outrage or offense, as our modern sensibilities might expect. The response was a soul-deep conviction of sin. This is the ground zero of all true revival.
What follows in our text is the blueprint for a healthy church. It is the gospel's chain reaction, moving from conviction to conversion, from baptism to belonging, from doctrine to devotion. This is not a description of a strange, one-off anomaly in the ancient world. This is normative Christianity. This is what happens when the Holy Spirit is poured out and the Word of God is preached with unvarnished power. We must therefore read this not as a quaint historical account, but as a direct challenge to the anemic state of much of the modern church. We are given here the essential elements of a Spirit-filled community, and we would do well to measure ourselves against this standard.
The Text
Now when they heard this, they were pierced to the heart, and said to Peter and the rest of the apostles, “Men, brothers, what should we do?” And Peter said to them, “Repent, and each of you be baptized in the name of Jesus Christ for the forgiveness of your sins; and you will receive the gift of the Holy Spirit. For the promise is for you and your children and for all who are far off, as many as the Lord our God will call to Himself.” And with many other words he solemnly bore witness and kept on exhorting them, saying, “Be saved from this crooked generation!” So then, those who had received his word were baptized; and that day there were added about three thousand souls. And they were continually devoting themselves to the apostles’ teaching and to the fellowship, to the breaking of bread and to the prayers. And fear came upon every soul; and many wonders and signs were taking place through the apostles. And all those who had believed were together and had all things in common; and they began selling their property and possessions and were dividing them up with all, as anyone might have need. And daily devoting themselves with one accord in the temple and breaking bread from house to house, they were taking their meals together with gladness and sincerity of heart, praising God and having favor with all the people. And the Lord was adding to their number daily those who were being saved.
(Acts 2:37-47 LSB)
The Necessary Wound (v. 37)
We begin with the response to Peter's sermon:
"Now when they heard this, they were pierced to the heart, and said to Peter and the rest of the apostles, 'Men, brothers, what should we do?'" (Acts 2:37)
The Word of God is a sword, and here we see it strike its intended target. The Greek word for "pierced to the heart" is sharp; it means to be stabbed, to be violently struck with compunction. This is not a mild case of the blues or a vague feeling of religious guilt. This is the Holy Spirit taking the truth of their sin, the murder of the Messiah, and driving it deep into their consciences. Before a man can be healed, he must first be wounded. Before he can be clothed in righteousness, he must see his own nakedness. The law must do its work, showing us our condemnation, before grace can be received as the astonishing gift that it is.
Their question is the cry of every truly convicted sinner: "What should we do?" This is not the question of a consumer asking about available religious services. It is the desperate plea of a drowning man asking for a lifeline. They recognize their guilt and their helplessness. They do not offer excuses. They do not try to bargain with God. They throw themselves on the mercy of the court and ask for the terms of surrender. This is the necessary starting point of true conversion.
The Apostolic Prescription (v. 38-40)
Peter's answer is direct, authoritative, and packed with covenantal theology.
"And Peter said to them, 'Repent, and each of you be baptized in the name of Jesus Christ for the forgiveness of your sins; and you will receive the gift of the Holy Spirit. For the promise is for you and your children and for all who are far off, as many as the Lord our God will call to Himself.'" (Acts 2:38-39)
The command is twofold: repent and be baptized. Repentance, metanoia, means a change of mind that results in a change of direction. It is turning away from your sin and your self-rule and turning to Christ as Lord. Baptism is the public sign and seal of this repentance. It is the uniform of the soldier of Christ, the visible mark of entry into the covenant community. Notice the purpose: "for the forgiveness of your sins." Baptism is not a mere symbol of a decision you made. It is an effectual sign, a means of grace through which God confers the blessings He promises. It is where God formally grants, in a visible and tangible way, the remission of sins to the penitent believer. It is the moment you are formally enlisted in Christ's army.
And with this comes a promise: "you will receive the gift of the Holy Spirit." The same Spirit who convicted them of sin now comes to dwell within them as a seal of their adoption and the power for their new life. But Peter does not stop there. He immediately defines the scope of this gospel promise in covenantal terms. "For the promise is for you and for your children." This is a direct echo of the Abrahamic covenant: "I will be a God to you and to your seed after you" (Gen. 17:7). The New Covenant does not shrink the boundaries of God's grace; it expands them. God has always dealt with families, with households. To tell these first-century Jews that the promise was for them and their children was to say that the covenant structure they had always known was still in effect. The sign has changed from circumcision to baptism, but God is still a God of generations. This verse is the bedrock of infant baptism. The promise extends to the children of believers, and they are therefore to receive the sign of the promise.
He extends it further, "and for all who are far off," meaning the Gentiles. But it is not a universal, automatic promise. It is for "as many as the Lord our God will call to Himself." Here is the beautiful tension of divine sovereignty and human responsibility. The call is broad, but the effectual call belongs to God alone. Peter then presses the point, exhorting them to "Be saved from this crooked generation!" The gospel call is always a call to come out, to be separate from a world in rebellion against its rightful King.
The New Community's Devotion (v. 41-42)
The response to this call was immediate and massive, and it resulted in the formation of a distinct and devoted community.
"So then, those who had received his word were baptized; and that day there were added about three thousand souls. And they were continually devoting themselves to the apostles’ teaching and to the fellowship, to the breaking of bread and to the prayers." (Acts 2:41-42)
Three thousand were baptized. This was not a slow trickle; it was a flood. The kingdom advanced dramatically. And these new converts were not left to fend for themselves. They were immediately incorporated into the life of the church and devoted themselves to four key activities. First, the apostles' teaching. The new church was a school before it was anything else. They were hungry for doctrine. A church that is not grounded in the truth of God's Word is a jellyfish, beautiful but spineless and toxic. Second, fellowship (koinonia). This is not just coffee after the service. This is shared life, a deep partnership in the gospel. Third, the breaking of bread. This almost certainly refers to the Lord's Supper, the covenant renewal meal that bound them together and to their Lord. And fourth, the prayers. They were a people dependent on God, constantly in communication with their commander.
The Character of the Church (v. 43-47)
The final verses describe the atmosphere and the impact of this new community.
"And fear came upon every soul... And all those who had believed were together and had all things in common... And the Lord was adding to their number daily those who were being saved." (Acts 2:43-47)
A sense of holy fear, of awe, fell upon everyone, both inside and outside the church. When God is palpably at work, it is a fearsome thing. This was accompanied by signs and wonders, which served to authenticate the apostles' message. But the greatest sign was the life of the church itself. "And all those who had believed were together and had all things in common."
Now, we must be very clear here. This was not communism. Communism is forced sharing, mandated by the state at the point of a gun, after the state has abolished private property. This was the exact opposite. This was voluntary generosity, flowing from hearts transformed by grace. These people still owned property, which is why they were able to sell it. Ananias and Sapphira are judged not for holding back a portion, but for lying about it, which Peter affirms was their right to keep (Acts 5:4). This was a radical, family-like love that saw a brother's need as its own. It was a temporary, emergency measure for a church gathered in Jerusalem from all over the world, awaiting Christ's imminent return to judge that city. But the principle is permanent: Christians are to be a people marked by sacrificial generosity.
Their life was marked by constant, joyful fellowship. They were in the temple daily, and breaking bread from house to house. Their piety was not a grim, monastic affair. It was characterized by "gladness and sincerity of heart." The Greek for sincerity is "singleness," without hypocrisy. They were the real deal. And the result? They were "praising God and having favor with all the people." Their joyful, ordered, generous lives were attractive. It was a powerful apologetic for the truth of the gospel.
"And the Lord was adding to their number daily those who were being saved." (Acts 2:47b)
This is the ultimate summary of church growth. The apostles preached, the people lived faithfully, but it was the Lord who did the saving. He added to the church. Evangelism is our task, but conversion is God's sovereign work. And He did it daily. The kingdom was on the march, and nothing could stop it.
Conclusion: A Church Worth Joining
This is the picture of the church in its first bloom. It was a learning church, a loving church, a worshipping church, and a praying church. It was a holy and awesome church, a generous church, a joyful church, and a growing church. This is what the gospel produces when it is truly believed.
The world is starving for this kind of authentic community. They are trying to replicate it with political tribes and online mobs, but it all turns to ash. The only true koinonia, the only true fellowship, is that which is found in Christ. It is a fellowship created by the Spirit, grounded in the truth, and expressed in sacrificial love.
The call to us is the same call Peter gave to that crowd. It is a call to repent of our self-rule and our participation in this crooked generation. It is a call to be baptized into the name of the Father, the Son, and the Holy Spirit, and to be joined to His body. It is a call to devote ourselves to the Word, to one another, to the Table, and to prayer. And as we do this, we will find that same gladness and singleness of heart. And the Lord, in His good time and in His sovereign power, will add to our number daily those who are being saved.