This was a potentially severe change from the customs they had known and practiced. He was the man who had opened the door for the Gentiles through faith and without circumcision and Law-keeping. Peter was first among the Twelve. The evidence of God's view is that He gave the Gentile household of Cornelius the Holy Spirit . This was also being led by the Holy Spirit .
Faith is the operative word.
The Judaizers wanted to burden the disciples with keeping the Law. One example is the extensive dietary rules of the Law. On this note of grace, Peter drops from Luke's narration and we do not hear from him again in Acts. The second speaker or speakers were Barnabas and Paul reporting what God had been doing with them. The miracles were God's certification of their teaching and work.