That is a human idea, not God's revelation. It happens today. How this was answered by the disciples. John the Baptist confessed the same. Jesus told Peter that this confession came to him only by God's revelation.
Christians are sinners like all people.
Their confession is a gift of God which comes to them through the Word of God. How this is answered in our time. Every time we come to church we confess with all true believers of all ages that Jesus is the Christ, true God and true man. The one, true faith unites us with Christians all over the world and with the saints in heaven. They repent of their sins.