What is your definition of good behaviour?
On what do you base your objective moral code?
There are two distinct possibilities regarding god and morality (pretending that god exists here):
1. There exists an Objective Moral Code outside of god. God is a moral creature and chooses to adopt this moral code as his own. This makes God a good being.
2. There is no Objective Moral Code. The things that God says are good and the things that God says are bad are picked completely at random by god, without him being subject to any higher sense of rightness.
If (1) is true (which most sober theists would agree with if they ever stopped to consider these two options), then we don't ever need to discuss God when it comes to morality. It exists outside of him, and we should question our moral senses to understand how God came to know right from wrong, emulating his choices.
If (2) is true (this really stinks), then it means that there is no such thing as right and wrong, there is just the following of rules picked arbitrarily by a father-figure who will punish or reward us based on our ability to follow these random rules.
In both cases, God has nothing to say about morality. And I do not see how a third case can logically be presented except as a slight modification of these two sets.
My objective moral sense comes from my understanding of evolutionary psychology, coupled with empathy. It is a system dubbed the "Moral Sphere" by a philosopher whose name I can't recall right now. Here's how it works: The person that breaks the moral sphere is bad, the person that upholds it is good. And the moral sphere is made up of our own freedom to exist and pursue happiness. The only things that we can do wrong is to impinge on the freedom and happiness of others.
This is more often stated in the various guises of the Golden Rule, a version of which every major religion seems to have. Treat others as you would like yourself to be treated. But, not in a selfish sense of reciprocity, but in an empathic sense of knowing what would harm yourself and not wishing harm on others.
That is the Objective Moral Truth. The rest is the details of what each society decides is the Moral Sphere of the moment. Those particular actions are what confuse for subjective moral sense, they are nothing of the sort. The Morality comes from how you make other people feel, not what tools you use to effect this feeling.