Jesus said to him in reply,
"Blessed are you, Simon son of Jonah.
For flesh and blood has not revealed this to you, but my heavenly Father.
"Flesh and blood has not revealed this to you," Peter did not come to realize who Jesus was from other men. He didn't learn this through his own accord. He came to this understanding through the heavenly Father. He needed the graces and faith from the Lord to be able to make the statement that Jesus is the Son God. He had to have faith he could not come to this answer on his own.
Just like Peter needed faith from the Lord to truly follow Christ, we need the Lord to help us follow Christ's teachings today. We could just go out on our own and try to be good people and follow all Christ's teachings but it will be awfully hard. But we don't have to do it alone. We have the help and guidance from the Lord to support us along the way.
If we try to understand everything on our own we are neglecting the amazing gift of faith that the Lord has given us.
Dear Lord, Help me to trust in you even when I can not understand on my own.