Something ive been thinking about

The more I learn about judaism the more I wonder where tf christianity got all its bad shit. I am not religous in any way but, i cant help but think about it. Why is divorce a sin in christianity when judaism has recognized the right to divorce for nearly a millennia and has codified religious laws for it. Why does christianity consider sex to be dirty (to the point where puritans considered it a sin to enjoy having sex with your own spouse) when in judaism it's considered holy and it's a literal mitzvah to have sex with your spouse on the sabbath. Why does christianity consider it a sign that you're faithless if you question your religion when in judaism that's considered an essential part to developing your faith. I'm probably stating the obvious here but I still can't get over the fact that there's no historical basis to any of this shit before christianity started, it's like christians just said "hey guys what if we took the torah and built a new religion around it but this time it was actively hostile to human life" 

(This isn't referring to any individual christians!! I'm speaking on my own religious trauma and such)