I still don't see how mentioning Leviticus is an argument. Christians would agree that Leviticus exists, but they wouldn't see it as a problem, as they try not to look at it out of context or uncharitably. It's easy to spin other peoples words, especially when not paying attention to the context. It's likely that there are precepts you hold about Leviticus which are incorrect, but because they were not mentioned, are not addressable. The fact that you can't get things to add up could mean that you aren't doing the math right. I'm wondering what you think the message of Jesus was if you reject books he adored. I also don't see the connection you are drawing between your confusion and division of Christians and the existence of apostates. There are other explanations for those concepts which make more sense to me, which I won't get into now unless you want to.
Here's another argument for you.. If an all powerful God wanted to communicate to people who would follow him, then it follows that the people who he wanted to give the message to would have the message the all powerful God would want them to have. If you accept that an all powerful God wanted to communicate, then it's a question of whether or not an all powerful God can fail, which would be self refuting if you thought he could fail. So if one already has reason to believe that the religion of Jesus was from God, then it would follow that followers of Jesus would have whatever communication God wanted them to have, in whatever form he wanted them to have it. It's not surprising that God would use something as plain as human accounts transmitted textually when Jesus himself spoke in parables instead of being totally open with his message.