I don’t think people who find things in the Old Testament and say, “Looky here, that’s a sin” fully understand what it means to be Christian. What’s in the Old Testament is just a bunch old Jewish laws. Christians are now ‘above’ the law. Consider that Jesus Christ was completely without sin and yet he frequently and flagrantly broke many of the Old Testament laws. Sinning is not so much what you do but why you do it. Love God more than anything and love your neighbor at least as much as yourself. Do those two things and everything else is pretty much optional.
I believe God lets us stumble along, slowly finding our way, and giving us chances to pick each other up.