That notion of a clear sense of right and wrong is precisely what makes some sort of religious belief essential, as there is no room for morals with some objective evaluator. The issue is, which religion teaches the true morality? That depends on identifying the right moral framework, but there are critical failures to every philosophical framework. Consequentialism robs morality of anything but number crunching, deontology robs morality of flexibility and responsiveness, various subjective frames of morality end up unable to condemn even the most heinous actions...of them all, eudemonism comes the closest. But the thing that's missing from eudemonism is a clear human ideal for which we our purpose is revealed. Which is what Christianity adds, a clear purpose for humanity: to be conformed to the image of Christ.
That doesn't mean that within Christianity there aren't deeply flawed teachings that can be morally troubling, but God named His people Israel(contends with God) for a reason. And that reason wasn't to slavishly follow instructions without developing our own consciences, but to wrestle with Him on matters of conscience until we either understand His reason or recognize our own insufficiency to judge Him. There are positions within Christianity that address many of the things you express as finding intolerable, such as the teaching that people will be judged according to what they have done with what they had instruction wise. God knows that we are but blades of grass, springing up for a season only to wither away again. He demands that humans use honest measurements, and so we can expect Him to do the same.
