The beginning of the church was when Peter opened the doors to the kingdom (church) with the keys (The Gospel) and those who obey the Gospel on earth will be held to in heaven, those who do not obey the Gospel on earth will be held to in heaven (Mat. 16:19)
Matthew 16:19 (NKJV)
And I will give you the keys of the kingdom of heaven, and whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven."
Peter opened the doors to the Church with the Gospel (Keys), those that obeyed the gospel were added (by the Lord) to the church, those who repented and were baptized received the indwelling of the Holy Spirit :
Acts 2:38 (NKJV)
Then Peter said to them, "Repent, and let every one of you be baptized in the name of Jesus Christ for the remission of sins; and you shall receive the gift of the Holy Spirit.
And Peter came to see himself in error when he said I perceive God has no respect of persons:
Acts 10:34 Then Peter opened
his mouth, and said, Of a truth I perceive that God is no
respecter of
persons:
peter had recently gone on and went ot the Gentile house and saw what happened how this Holy Ghost fell on them without any rituals done, read Acts 9-11 to get that context please, I think it important. And is why Peter said that water baptism was good, not for removing sins, but as a good conscience to God. He changed his thought on the subject after seeing what he saw
1 Peter 3:21 The like figure whereunto
even baptism doth also now save us (not the putting away of the filth of the flesh, but the answer of a
good conscience toward
God,) by the resurrection of Jesus Christ:
Peter being in flesh like me and you had to discern truth, and did. Even Christ said to Peter that Satan wished to sift him like wheat, and said Chirst he prayed for his Faith, and when he returned from that battle, he would strengthen the brethren.
And Peter by far is not the only person ever used by God, there are many Saints, as well that had to learn truth over error
Luke 22:31 “Simon, Simon,
Satan has asked to have
you, to
sift you like wheat,
Luke 22:32 but I have pleaded in prayer for you
that your faith should not completely fail. So when you have repented and turned to me again, strengthen and build up the
faith of
your brothers.”
Only Father can reveal this truth over man's mix of error into truth, praying and knowing Father will do this for all that Father sees to do this for, knowing each and their true motives