Peter was not God, but he also walked on the water, taking his faith and acting on it. Jesus said Peter was of little faith. He did not say NO faith, for Peter did show faith. But he failed to show it fully and consistently. Faith, then, is an obedient response to God's Word.
Fear comes in the absence of faith.
In fact, fear can be said to BE the absence of faith. It comes from disobedience to God's Word. Reading is great, but not enough. Study is ordered, but not enough. That's why God ordains preachers, teachers, and prophets.