Matt 16:13-18 Now when Jesus came into the district of Caesarea Philippi, he asked his disciples, "Who do people say that the Son of Man is?" And they said, "Some say John the Baptist others say Elijah, and others Jeremiah or one of the prophets." He said to them, "But who do you say that I am?" Simon Peter replied, "You are the Christ, the Son of the living God." And 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 I tell you, you are Peter, and on this rock I will build my church and the gates of hell shall not prevail against it."
This alone shows that the expression Son of God means more than a spokesperson for God, as were the prophets. It declares his deity. And it is not knowledge that the human mind on its own (flesh and blood) can or does grasp. It is something that must be and is revealed to them by God himself. IOW, he must open the eyes of their heart to see it. It is also the very foundation of Christ's church---(Christianity. Those in Christ through faith). To be a Christian, one who belongs to Christ, means more than to be a follower of Christ in a loose sense of the word. Many follow his moral teachings, but do not believe that he is God. Until the Father reveals "Who do people say that the Son of Man is?" he is just another prophet, or a good man, or a teacher---just man.
The deity of Christ is the very rock upon which his church is built.