Jesus also said, “The law was made for the man, not the man for the law.” He disobeys the law more than once and asks his disciples to do the same. Then, after Jesus’s death, Peter is instructed to disobey the law even more. So no, the Bible is quite clear that when Jesus says, “Until heaven and earth pass away, not an iota, not a dot, will pass from the Law until all is accomplished,” he doesn’t mean that all the horrific commandments we find in the Bible must be obeyed. Just a few verses later, Jesus even changes the law!
You can always take verses out of context (both literary and historical) and make anything look horrible. Here, Matthew is actually doing the opposite of what you think. When he writes, “Whoever relaxes one of the least of these commandments and teaches others to do the same will be called least in the kingdom of heaven,” he isn’t addressing u/FuglyDuck, an American from the 21^st^ century, but people of his own time. He’s saying that those who “relax one of the least of these commandments and teach others to do the same” will still enter the kingdom, while many Jews of his time believed they wouldn’t enter it at all.
And right after that, he says, “Unless your righteousness exceeds that of the scribes and Pharisees, you will never enter the kingdom of heaven.” Yet the scribes and Pharisees were well known for their meticulous observance of the letter of the law. So he’s saying that people who observe the letter of the law won’t enter the kingdom of heaven, while those who “relax” the “commandments” will! You see, if you read the text thoughtfully and take its context into account, it says something quite different. It's convoluted indeed, but that's the literary style of the time. You can't make strong assertions like that without studying the subject a minimum. You can't read 2000 years old texts like they were written yesterday. Even in translation, they have to be decoded.
I have no idea what you mean when you say that Jesus explicitly “cited a law that directs people to stone kids who talk back.” There’s no law in the Old Testament that says that. There’s Deuteronomy 21:18–21, which is a pretty bad law, and as far as I know, Jesus doesn’t cite it. But this law doesn’t speak about children: the “kid” in question is described, among other things, as someone who drinks alcohol. He isn’t a little child. But yes, Deuteronomy 21:18–21 is a shitty text, even without your exaggerations. There are other bad texts in the Bible, and not only in the Old Testament. But they have to be read in context.
For example, you say the Bible “says it’s totally cool to sell your daughters as sex slaves.” I assume you’re talking about Exodus 21:7–11. It’s another shitty law by our standards, but at the time it was a step forward: it protects women who were sold. Yes, selling a daughter is a horrible practice, but it was the norm for much of human history. The Bible wasn’t written in a cultural vacuum. It takes people’s practices as they are and tries to push things in the right direction. And it worked! We moved in the right direction, so those laws now seem backward. They seem backward because they succeeded. Jesus says as much in Matthew 19: the law was imperfect because it was given to an imperfect people. And when Jesus gives a commandment himself, it’s still the same principle.
But what you don’t understand is that only a small part of Christianity considers the Bible to be the “inerrant Word of God.” Jesus didn’t, and neither do “progressive Christians.” So no, my analogy still holds. You’re applying something that’s true of only one part of Christianity to all Christians, and that’s intellectually dishonest. Your criticism is completely justified when directed at people who believe God actually approves of killing people or selling slaves. But that doesn’t describe most of us. We objectively do not worship the God you’re describing.