So, let me get this straight: A god sacrifices its only son, purportedly so that it (an ultra-powerful god) will be in a position to forgive us (comparatively powerless humans) for something called "sin".
I don't think so.
I really and truly don't think so.
Imagine for a moment that you've put a lot of work into your yard, and it looks fabulous.
You put up a sign that says "Keep Off the Grass".
Along come a couple of people who don't know how to read. They not only walk across your lawn, but sample a raspberry or two off the bush on the north side of the walk.
You get annoyed.
No; you get angry.
So psychotically angry, in fact, that you lock the great-great-great-grandkids of the trespassing raspberry thieves in your basement, turn on the garden hose, and drown them all. (All, that is, except for a dozen or so kids who were out at the lake that afternoon.)
The survivors go on to raise families, and many generations later you send your son to chat with them. As you're omniscient, it really shouldn't come as much of a surprise when your kidlet gets nailed to a tree.
(Although the dead fruit tree, the herd of pigs rotting in a culvert, the fist fight at the ATM, that police report about a couple of stolen motorcycles and rumours about your son calling some woman a bitch might also have given you a bit of a heads-up...)
This time, instead of killing the lot of them, you say that you "forgive" them.
But only till next week, when you intend to send death, disease, pestilence, famine, war, lambs and dragons and Beasts (oh my!) to liven things up in the neighbourhood.
Literalist Christians, give me a break. The key stories in your mythology are abysmally, terminally stupid. You should be ashamed of yourselves for believing such tripe, and deeply ashamed if you teach these stories to your kids as "The Truth."
Metaphor-friendly Christians, you aren't off the hook either. You have yet to explain how an all-powerful god could possibly have been injured by humanity acquiring any amount of knowledge, with or without the god's permission.
For that matter, you can start by explaining why an all-powerful, omniscient god would bother to put two rather useful trees into a garden, yet become upset when one of them gets used by people who didn't yet possess the knowledge to know they were doing something wrong.
And then you can try to explain how a blood sacrifice makes everything hunky-dory again, but only if we think blood sacrifice is a good thing and agree to play along with this nasty psychotic deity and its creepy obsessions.
End of rant. Discuss.