Acts 4:1-4 meaning

Having just healed a lame man in the temple courtyard, Peter and John attract a large crowd of people.

As Peter and John were preaching the gospel of Jesus, speaking to the people in the temple courtyard, the priests and the captain of the temple guard and the Sadducees came up to them. This alliance of priests, temple guard, and Sadducees were greatly annoyed because Peter and John were teaching the people and proclaiming in Jesus the resurrection of the dead. The captain of the temple guard is basically the chief of police, just underneath the high priest in power. This group constituted the political powers that ruled the temple.

The Sadducees and the Pharisees have their root in the Maccabean revolt (roughly 160 BC). The Greek rulers, the Seleucids, under Antiochus Epiphanes, had decided that they wanted to wipe out Judaism, and they made Jewish practice illegal. So the priests, the Maccabees, started a revolt that seemed doomed to fail, but God intervened and miraculously saved Judaism. Israel became an independent kingdom once more, where different political and religious sects emerged. Eventually, Rome would take over Israel in 63 BC, largely due to competition between competing Jewish factions, but the Pharisees and Sadducees retained power over the temple and had sway with the Roman leadership, as well as the common people.

So the Pharisees and the Sadducees were descended from these national heroes, and both have their roots in the Maccabees' tremendous effort to save Judaism. But now their aim had become twisted, for it was in the name of saving Judaism that they crucified Jesus (John 11:48). So they wandered away from walking with God and seeking His will. Had they been seeking the will of God, they would have recognized Jesus as the Messiah, not as a political enemy.

Even so, at the time of Jesus, the Pharisees were actually well respected by the people of Israel. This can be observed in this interaction between Jesus and His disciples:

"Then the disciples came and said to Him, 'Do You know that the Pharisees were offended when they heard this statement?'"
(Matthew 15:12)

In this passage from Matthew 15 it is apparent that the Pharisees' offense was something the disciples assumed was problematic, indicating their respect for them.

The Sadducees were not popular, however, because they were the priesthood and the high priesthood, and had turned worship at the temple into a money-making scheme, as Jesus noted when He ransacked the market at the temple:

"And He entered the temple and began to drive out those who were buying and selling in the temple, and overturned the tables of the money changers and the seats of those who were selling doves; and He would not permit anyone to carry merchandise through the temple. And He began to teach and say to them, "Is it not written, 'My house shall be called a house of prayer for all the nations'? But you have made it a robbers' den.'"
(Mark 11:15-17)

Jesus Himself condemned the leadership of the Sadducees, comparing them to serpents (Matthew 3:8), and told His disciples not to listen to their teaching (Matthew 16:12).

The Sadducees are mentioned here, and not the Pharisees, likely because this episode is occurring in the Temple, which was controlled by the Sadducees. The Sadducees might have been particularly upset with Peter and John because they believed that the Messianic Kingdom started with the Maccabean victory over Antiochus Epiphanes, and that they (the Sadducees) are ruling and reigning in place of the Messiah, and that there is no Messiah to come. They control the Temple, and in their eyes Peter and John are spouting heresy. They did not believe in a resurrection (Acts 23:8). Given this posture, it is understandable that they are greatly disturbed because Peter is teaching the people and proclaiming in Jesus the resurrection from the dead.

Peter is not only explicitly teaching that resurrection is real, but that Jesus Himself was resurrected, whom the Pharisees and Sadducees put to death just a few weeks earlier. That Jesus was resurrected is a blow to the doctrine of the Sadducees and a dismissal of their power. They do not want the Jewish people hearing this teaching because it threatens their authority over the people, if believed.

So they laid hands on Peter and John and put them in jail until the next day, for it was already evening.

Those who had arrested Peter and John wanted to bring the whole Sanhedrin (Jewish ruling council) together and put them on trial, as they had with Jesus. The Sanhedrin was composed of seventy Pharisees and Sadducees, the religious leaders that controlled Israel. But it was already evening, too late in the day to assemble a council, so for the time being they put Peter and John in jail. And yet many of those who had heard Peter's message believed; and the number of the men who believed in Jesus as the Messiah came to be about five thousand.

Five thousand men believed and joined the early church. These would all have been Jewish believers. This number does not appear to include the women or the children who also might have believed on that day. There was a large number of people believing the Gospel, when they saw this man who has been lame his whole life suddenly healed. Presumably they have repented, as Peter urged them to (Acts 3:19). They see now that Jesus, who had been put to death by the Jewish leaders and crowds, was indeed God's Messiah, and was alive, and was healing the infirm even as He had during His ministry, showing that He brings life and restoration, refreshing and return to God (Acts 3:20-21, 26).

We will see throughout Acts that the gospel is presented to Jews by asking them to repent. The Jews believed in God and His word. They needed to repent of not following God, for if they follow God they will follow His Son. The Gentiles are asked to believe. Gentiles believed in pagan gods that could be manipulated, and who provided moral justification for immoral behavior. In either case, it is Jesus's death and resurrection that saves (John 3:14-16).