Who revealed that to you? Jesus said Peter was blessed because God revealed to him who Jesus really was:
Matthew 16:15-17 (WEB):
(15) He said to them, “But who do you say that I am?”
(16) Simon Peter answered, “You are the Christ, the Son of the living God.”
(17) Jesus answered him, “Blessed are you, Simon Bar Jonah, for flesh and blood has not revealed this to you, but my Father who is in heaven.
And how did God reveal this to Peter? Was it by demons?
Matthew 8:28-29 (WEB):
(28) When he came to the other side, into the country of the Gergesenes, two people possessed by demons met him there, coming out of the tombs, exceedingly fierce, so that nobody could pass that way.
(29) Behold, they cried out, saying, “What do we have to do with you, Jesus, Son of God? Have you come here to torment us before the time?”
and Mark 3:11 (WEB):
(11) The unclean spirits, whenever they saw him, fell down before him, and cried, “You are the Son of God!”
Peter answered Jesus, but the other disciples believed it too. After the walking on water event:
Matthew 14:33 (WEB):
(33) Those who were in the boat came and worshiped him, saying, “You are truly the Son of God!”