"PTR found an example of your book wherein the execution of disobedient children is spelled out discretely."
Indeed, the passage does exactly that. However, a key understanding of the bible is that the New Testament explicitly "retcons" the Old Testaments laws and legal structures. I explained this a bit more at length in my reply to PTR's comment elsewhere in this thread, and I would prefer not to type it out again to avoid clutter, but I do think it's a key point that explains why that passage doesn't cause me mental friction.
The O.T. Israelites had only the Law and their adherence to it to redeem them/get to heaven/be godly. Jesus' Big Claim is that his death and resurrection as atonement for all mankind forever replaces the Law with His Love. Even if you don't beleive in Jesus, this retroactively changes the way that we must scholarly read a lot of the O.T. passages, especially when they are prescriptive or legalistic in nature. The contradictions don't matter in the light of Jesus' paradigm shift. The moral codes of a Christian are vastly different than the moral codes of a pre-Christ Jew, and this is important. Where the morality comes from is different.
The book is the word of God, and the "no bueno" parts are therefore read in an incomplete or context-lacking manner that doesn't take this very important N.T. reality into account. Someone who points to Zachariah and Elizabeth to justify child sexual abuse is blatantly misreading the bible. This is something both you and I agree on. But you use this misreading to claim that the seeming contradiction discredits the rest of the book, whereas I claim the seeming contradiction is actually a misunderstanding of the way the N.T. informs the O.T.
I'd also like to point out that if someone were to discount "everything [I] have to say" because I claim that my "book gives me [(more specifically, the religion or the philosophy, and person of Christ, I follow)] moral supremacy", then I'd say that person is unreasonable. Literally, that person is unwilling to reason with me further because of a single claim. That's not my problem - that's a lack of critical thought and and uncharitable way to engage with other people.
protip: I don't think I'm better than anyone. Christianity teaches me that I'm not. God tells me I'm no better than you. That's a foundational tenant of Christian worldview. You put word in my mouth when you say things like that.
You certainly don't see no Jesus, and that's fine. If you looked, with an honest vulnerability and humility that you don't already know the truth about everything (not to imply that you do think so, just saying that's part of the journey for anyone), you'd find Him in some way that He revealed Himself to you. Part of Christian understanding is that the free will we're granted means we have to open the door and let him in. He's not going to barge in and shout in your face about how you need to believe in Him. He doesn't need me interpreting for Him, but He has called His people to proclaim the truth, whatever that may be.
Thanks for reading if you made it this far :)