I seemed to disagree with God and I thought this was my fault. I had a problem with the story of Pinchas, but I thought that was me just being "soft" or "secularized" and I was really unsure whether to trust my own sense of morality.

If you replace God with Yudkowsky, story of Pinchas with AI going FOOM and soft, respectively secularized, with irrational and sense of morality with education (or worse, intelligence), then you got how I feel about another topic.

What changed my mind is a sense that my brain is all I've got. I may be wrong about many things, but I'm not going to become less wrong by throwing out the majority of what I know in favor of one ancient and rather bloody book; if "conscience" isn't trustworthy, it's still probably more trustworthy than simple conformism.

I've always felt that conscience was just a matter of taste. So it was never really a question about how trustworthy my moral judgement is but that I care about it. I abjured God when I still believed that it exists. Only later I became an atheist. I suppose that is the difference between you and me here. You wanted to do the right thing (in an objective sense) and for me the right thing has always been that what I want.