I'm an atheist, so God and I have no relationship.
I'm going to assume that when you say "symbiotic or parasitic relationship", you mean that God is either a parasite, or trying to be helpful to humanity. But I'm going to be literalist right now, just for the fun of it, and say that I don't know if humanity is a parasite of God, because I haven't the slightest idea what God is like.