What Part Did Paul Play In The Early Church?

You can find all you want to know about the apostle Paul by reading the books of Acts, and Romans. Hope this is helpful.   Best wishes and God Bless

The Apostle Paul was a committed Jew who had the good fortune to be born a Roman citizen.  He came from Tarsus, which was in Cilicia, not in Palestine.  Sometime around or just after the crucifixion and resurrection of Jesus, he came to Jerusalem to study under the Rabbi, Gamaliel.  He was a bitter opponent of the emerging church, regarding it as a blasphemous and wicked movement.  He was very zealous in hounding out christians and having them imprisoned.  He was on his way to Damascus, with letters of authorisation from the Jewish authorities, to find and arrest as many christians as he could when he himself was arrested by a vision of the risen Lord Jesus.  He became a christian from that time, and one of the foremost christian missionaries of all time.

With various other helpers, including Barnabas, Silas, John Mark, Luke and Acquila and his wife Priscilla, he travelled widely in the European part of the Mediterranean, getting at least as far as Rome.  He may even have got as far as Spain.  Wherever he went he established churches of his converts to faith in Jesus in important population centres, with view to those churches in turn evangelizing the more rural areas around them.   He was particularly equipped to evangelise non-Jewish people, being a Greek by culture and a Roman citizen by birth, and he regarded himself as "the Apostle to the Gentiles" (non Jews) more than all the others.

He wrote a number of letters to some of these churches, and also to some of his associates, in which he addresses problems they have and, above all, codifies the teachings of Jesus into a structured doctrinal system.  Peter, James, John and the writer to the Hebrews did some of this as well, but pre-eminently this was Paul's main contribution to the Church.