Paul had been taken before Felix, the governor of the area, to stand trial and avoid the lynching that the Jews had planned for him. After some time, Ananias, the high priest, and some of the elders came to level their accusations at him and accused him of starting riots and desecrating the temple, neither of which had Paul actually done.
As Paul took his turn at his defense, he took the opportunity to speak of what he believed, explaining even that he was actually not opposed to what the Jews spiritually believed, but instead whole-heartedly agreed with them. So much so that he looked all of the way back into the beginning and foundations of both their faith and his, that which we call the Old Testament today, but which Paul simply referred to as the Law and the Prophets:
However, I admit that I worship the God of our ancestors as a follower of the Way, which they call a sect. I believe everything that is in accordance with the Law and that is written in the Prophets, and I have the same hope in God as these men themselves have, that there will be a resurrection of both the righteous and the wicked.
Matthew 24:14-15
Paul is explaining that he, as a Pharisee, but also a follower of the Way – a way of saying that he is a Christian – believed what they believed as well. He believed in the resurrection. He believed that the Law the Prophets were not opposed to what he believed. Instead, he believed that they specifically pointed toward Jesus!
The Sadducees and the Pharisees were the ruling parties within the Sanhedrin. They had many differences, but for context and to highlight what Paul is saying, some of the most notable were these:
The Sadducees did not believe in an afterlife. The Pharisees believed in a punishment or reward by God for the life that you lived on earth.
The Sadducees, therefore, neither believed in the possibility of the resurrection, but the Pharisees did.
The Sadducees did not believe in a spiritual world with angels and demons, whereas the Pharisees did.
Paul had a background as a Pharisee. He grew up a Pharisee and most certainly believed in the afterlife, but based on his encounter with Jesus and understanding of the reason that Jesus had come, Paul had broken with the Pharisaical view that a person’s reward or punishment in the afterlife was simply based on whether they were good or bad people, or whether they had committed too many sins that God wouldn’t forgive and allow the person to enter heaven.
Instead, Paul followed the Way, a name presumably taken from Jesus’s statement in John 14:6 that he is the way, the truth, and the life. This group went well beyond the Pharisees, believing that Jesus fulfilled the Law of Moses, to which the Pharisees and Sadducees supposedly adhered. Jesus, unlike any other person ever to walk the earth, never sinned. He followed the Law completely and was therefore perfect. No man could do this, yet Jesus was not only a man. He was born of the Holy Spirit, not from a man, and so he was both a man and God himself.
Paul said that he also believed the Prophets. The Prophets made many claims about what the Messiah would do, and those claims, those prophecies, were fulfilled, both in the purpose and in the specific actions of Jesus. The Prophets claimed that the Messiah would be, for example, born from a virgin, would be killed, and would rise again from the dead, among many other actions. Of course, each of these things came true in Jesus Christ.
So Paul claims that he is in direct agreement with the Law and the Prophets. In fact, he might have even thought that he believed them even more than the other Pharisees because he believed that they were both true, and that the prophecies had actually come true! The books of the Law and the Prophets had become true in the person of Jesus, and this is what Paul based both his faith and all of the rest of his life.