Just because you know how to loose weight, doesn’t mean you loose weight. Why? Knowing is in your head, doing is in your heart, your desire to act and do.
Faith is the same. Just because you claim to know of God, accept Jesus as a person in history, understand the good, doesn’t mean you have it in your heart. Having it in your heart is all that matters to God. He knows your heart. When you get him, Jesus in your heart, you will understand, see the world differently, have God see you through Jesus and differently than you are before being a Christian.