I accept that you genuinely believe that yours is the one true God, that your actions are based on your sincere belief that this is His will and that you thus believe such actions to be divinely jusified.
I also accept that other people who undertake actions we might both find reprehensible (e.g. Muslim suicide bombers) sincerely believe that their actions are the will of the God they genuinely believe to be true and that they consider their actions to be also divinely justified.
The probem is that with all this divine justification and proclaimed yet contradictory claims of knowing the will of the true God going on we can't possibly satisfy everyone in the laws we formulate can we?
So what do we do?
Well we could pick one of these belief systems, sign up to one particular "will of God" and base our laws on that. This is what Islamist fundamentalists who want to impose Shariah law would like. This is presumably what Christians such as yourself would like. We could go the theocracy route. We could do that.
Or we could ignore all this self proclaimed knowledge about the will of God and base our laws on the idea that everyone has a right to believe what they want but not to impose their particular beliefs and prejudices on others. This is called the secularist route.
Neither option will satisfy everyone. The theocracy route will only please those who follow that very specific and particular form of theism. The secular route will fail to please those such as yourself who think their particular form of theism should hold special privelige.
It ultimately boils down to you wanting your belief system to have special privelige and being very upset and frustrated that not everybody else agrees that you and your particular ilk have special knoweldge of the will of God. But every theocratist feels the same.