Guilt-free if only God-free?

Nietzsche brings up the idea that the worship and acknowledgment of God, or higher being, causes mankind to feel guilty. That man sees Gods as "the ultimate antithesis of his own ineluctable animal instincts." With this man knows he can never stand up to the godly standards and that he is a mere mortal with an animal nature for which he will never escape. It is like a disability, this thinking, says Nietzsche because it only leaves man feeling guilty about his disposition, which he has limited control over. Instinct in its very definition means something that is inherent, not learned or practiced by choice.

But would we really be without guilt if there was no belief in God? This question seems unanswerable since we have no idea how life would be without the presence of God in society. But I think we would still have guilt. God is just the excuse we've made to blame this guilt on. The guilt come from within us, our own consciousness and self-awareness. We create the guilt because we have seen the consequences of our own actions. Even, without the godly standard from which we compare ourselves, I think the "pain" in our memories, like mnemotechnics, is enough to create a sense of guilt.