After I was born again into his family by faith, I began my walk with him. When I sin, either in word, deed, or thought, I put up a wall between us and because of my shame, I lose fellowship with him (never my eternal security - since it was never based upon my being sinless (as if) in the first place). He promises, though, that when I confess my sin (name it like he names it - no quibbling), he is faithful and just to forgive my sin and to cleanse me from all unrighteousness. My fellowship with him can be restored, and this is something he desires and grieves when it's lost.
This by no means is saying God winks at sin and I can just live as I please. Far from it. Besides the obvious physical consequences that can happen from sin, God is now my heavenly father, and he is a loving but strict parent. He won't let his kids get away with wrong. He disciplines just like a good father does, and the purpose is our own happiness and joy. He knows when we stray from him, we get hurt and he loves us too much to let us do that. Praise his name!