Why I Am Justified in Telling God What To Do?
Well I do dare to demand better of God, if he exists. That's the point. How am I to know he exists when his lack of divine forethought led to massive slaughter among Christians themselves over the stupidest of doctrinal trifles that if he had foreseen them and had even average communication skills he could have averted? Or, he could have told us more important things than what to do with our penises and vaginas, by giving us the knowledge to make vaccines and anesthesia for surgeries?
Why do I demand better things? It's simple:
If God created me as a reasonable human being, then I can doubt the reasonableness of a God who fails to give me what I need to believe as a reasonable human being.
If God created me as human being who seeks sufficient evidence to believe, then I can demand that he gives me the sufficient evidence I need to believe.
Connect the dots.
Of course, maybe he doesn't want reasonable people? Who knew? ;-) But then, why am I who I am? Still, if that's the case then he could snap his omnipotent fingers and take away my critical thinking skills so I would believe as others do. I did at one time. Then I grew a brain, just as ex-Mormons, ex-Muslims, ex-Orthodox Jews, ex-Scientologists and others did. ;-)