Just saying it does not make it true, you need to practice it.
Listen to 1 John 1:5-7
This is the message we heard from Jesus and now declare to you: God is light, and there is no darkness in him at all. So we are lying if we say we have fellowship with God but go on living in spiritual darkness; we are not practising the truth. But if we are living in the light, as God is in the light, then we have fellowship with each other, and the blood of Jesus, his Son, cleanses us from all sin.