Peter added many words of warning to his speech, as well as an appeal to the people to receive the Gospel, which boils down to "Be saved from this perverse generation."
The word translated as "perverse" is the opposite of "straight", indicating deviation from righteousness. Psalm 14:1 exclaims, "The fool has said in his heart, ‘There is no God.’ They are corrupt, they have done abominable works, there is none who does good." It is the picture of the world, at that time and now. Claiming that there is no God, and leaning now on the theories of evolution, the world no longer knows the rules of righteousness and justice God teaches in His Word.
A crowd of about three thousand people heard and heeded the call of Peter that day, were baptized and added to the church. Note that only those who had already received the Gospel message, and repented of their sins, were baptized.
Based only on verse 38, it might wrongly be concluded that the Holy Spirit will be given to converts after they are baptized in water. However, this contradicts other Bible passages. We find in the Bible different orders for four groups of converts:
Jews: repentance, baptism, receiving the H.S. (Acts 2:38, 22:16).
Samaritans: faith, baptism, prayer, laying on of hands, receiving the H.S. (Acts 8: 14-17).
Gentiles: faith, receiving the HS, baptism (Acts 10: 44-48).
Disciples of John the Baptist: faith, new baptism, laying on of hands, receiving the H.S. (Acts 19:1-7).
Jews today are treated the same as Gentiles, and there are no more Samaritans or disciples of John the Baptist. Thus, order "3" for the Gentiles remains for all, and agrees with the other biblical teachings given by the apostles.
The Holy Spirit is given immediately following faith, without interference from others. Baptism by water is not a requirement for salvation, but is a required public witness to faith by those who were saved.
There is no indication that only the apostles baptized: all members of the church could provide this service, in Jerusalem there were many public pools that could be used for baptisms, and these were not necessarily all done in one day.
The words of the Lord Jesus were fulfilled that day "I will make you fishers of men" (Matthew 4:19) and " Most assuredly, I say to you, he who believes in Me, the works that I do he will do also; and greater works than these he will do, because I go to My Father" (John 14:12).
This converted crowd dedicated itself to four activities, which are essential for any church, whether primitive or modern, new or mature:
The doctrine of the apostles: it was to His apostles that the Lord Jesus promised, "the Helper, the Holy Spirit, whom the Father will send in My name, He will teach you all things, and bring to your remembrance all things that I said to you" (John 14:26). The apostles, in turn, conveyed these teachings to all new converts, verbally and then in writing, and we find them in the Bible.
Communion: This is a translation from the Greek (Koinoniai), which means society or participation of a venture with others. For example, there is a participation in the blood of Christ (Philippians 2:1), in the work of evangelization (Phil 1:5), and in contribution to the needy (2 Corinthians 8:4, 9:13). New converts tightened the ties that bound them in their many activities, including the distribution of wealth (v.44), the Lord's Supper (1 Corinthians 10:16), and even common meals.
The “breaking of bread”: this is the translation of the Greek word klao that was used for a common meal. This same word came to be used for the Lord's Supper, which was held at first at the end of a meal in which all church members participated. Because of the problems which arose with this practice, church members were later instructed to eat their meals at home, and all to meet specifically for the Lord's Supper (1 Corinthians 11:22).
In prayer: in rooms (Acts 1:14), in the temple at Jerusalem (Acts 3:1) and in their homes (Acts 4:23), prayers are to be made to the Father in the name of the Son through the Holy Spirit (Ephesians 2:18), for worship, guidance, protection, intercession, thus demonstrating complete dependence on God.
Fear came upon every soul, as they were awed by the power the Holy Spirit was revealing overtly in their midst. He did many signs and wonders through the apostles, supernatural acts that confirmed the mandate given to them by the Lord Jesus.
Those who believed were united, and their fellowship embraced a general participation in their property, as “no one said that any of the things he possessed was his own, but they had all things in common” (chapter 4:32). This attitude only appeared in Jerusalem and was evidently due to the pressing circumstances in which the people lived there in those days.
By selling their possessions and goods and bringing the proceeds to the apostles to distribute to the needy, they proved they loved each other as themselves, which is the second greatest commandment (Mark 12:31). Natural selfishness had disappeared through love from knowledge of divine love, and their generosity was the fruit of the Holy Spirit that was in them now.
The believers also continued to attend the Jerusalem temple daily, persevering unanimously in their new faith. They were Jews, and the temple had always been the place where they would worship God. Although now belonging to the church of Christ, they were slow to leave the practice of the Old Testament and we see that the procedure lasted through the period covered by the book of Acts.
They ate their meals in their homes (some translations say "house to house" because the original can also mean that). They possibly met in different homes, exercising hospitality in that practice. Anyway, they showed joy and singleness (cleaning) of heart in all things, and praised God, attracting the attention of unbelievers and captivating the favour of all the people.
It was a short calm period, but it would not last long. Christian faith inevitably raises the hatred of the world for contrasting sin, and warning of the punishment to come if it continues. The disciples were warned by the Lord against the appreciation of the world (Luke 6:26), and of the persecution and tribulation they would suffer (Matthew 10:22-23). Shortly the religious leaders would realize the threat that this new "sect" represented to their position of religious authority, and begin their campaign to silence the apostles.
Meanwhile, the Lord was adding to the group those who were being saved. Note that it is God who gives growth to the church of Christ (1 Corinthians 3:7). There were daily conversions, and it was of those who heard the Gospel preached by the apostles and disciples, and received Jesus Christ as their personal Lord and Saviour. It was always based on their individual decision. Grace is from God, who extends them salvation upon their faith.
Although the word "church" was not used in this chapter, it is obvious that this was its beginning, and shortly after it is found in chapter 5:11, referring to those who had been converted to Christ and joined the group of apostles.
The temple was used at first for their meetings, but they also met in houses, of which all participated. They were home meetings where they worshipped together and taught the doctrine of the apostles (who transmitted what they had learned from Christ), received the messages of the prophets of God, and were taught by teachers or masters. All these ministers were given by God to the church for their education and spiritual growth (1 Corinthians 12:28).
From a human point of view, it might seem to have been suitable at that point to start an organization with a president, a board of directors, various executive councils, and numerous subsidiaries with their own administrative structures. There were thousands of converts who needed to be sorted and put to work in an orderly and controlled manner.
However, none of this was necessary, as the direction was of the Holy Spirit, infinitely more skilled than any human organization. "Only" with the use of dedicated servants endowed with the necessary gifts, the Holy Spirit performed a great growth of Christ's church in the first three centuries, overcoming incredible opposition from human and satanic forces, and it spread throughout the known world.
41 Then those who gladly received his word were baptized; and that day about three thousand souls were added to them.
42 And they continued steadfastly in the apostles' doctrine and fellowship, in the breaking of bread, and in prayers.
43 Then fear came upon every soul, and many wonders and signs were done through the apostles.
44 Now all who believed were together, and had all things in common,
45 and sold their possessions and goods, and divided them among all, as anyone had need.
46 So continuing daily with one accord in the temple, and breaking bread from house to house, they ate their food with gladness and simplicity of heart,
47 praising God and having favor with all the people. And the Lord added to the church daily those who were being saved.