When discussing this, I like to reference Matt. 16.
Christ asks the disciples "Who am I ?" This is after all the time they had spent together, all the things they had seen. And Peter answers "Thou art the Christ, the Son of the living God"
And what was Christs response? How does he say that Peter knew it? "Flesh and Bone hath not revealed it unto thee" Not th testimony of the Savior as to who he was, not the testimonies of the Prophets he had heard read. The Father had revealed it to him through prayer, the same way we have to learn it.