So, if the Old Testament is mostly a book of history for Christians, let's look at the character of Yahweh and some of his accomplishments as told in the books of the OT. These are a few highlights as I found so many examples it would make this post much too long.
Genesis:
Chapter 3: God curses all of mankind for a sin committed by Adam and Eve. Interestingly, eating of the tree would have "opened their eyes and made them as gods, knowing good and evil." If Adam and Eve didn't know good and evil before, how can God blame them for disobeying him? They were innocent, ignorant, uninformed, and even misled by God himself. He didn't bother giving them enough information to make a right decision, but instead, created them with human curiosity and weaknesses and placed the temptation there for them then allowed the serpent to seduce them, knowing in advance what would happen. He is omniscient, after all. They were set up and there is no other way to spin that. Then they were punished for something they were hardly responsible for - a punishment that certainly didn't fit the crime! The entire human race cursed, forever.
Chapter 6: God commits global genocide, destroying every living thing on the planet except Noah and his family and the animals on the ark. He regretted creating humans because they all turned out evil. (Really? ALL of them?) But being omniscient, didn't he know that was going to happen? And if he did, he created it that way to begin with. So, again, Yahweh punishes humans for HIS own mistake. And for good measure, he kills all the other living creatures as well.
Chapter 19: God's angels visit Lot in Sodom to warn him that God is going to destroy the city. The men of the city surround Lot's house, demanding he send the angels out so they can "know" them but Lot (the only man God finds righteous in the city) "righteously" offers to send his virgin daughters out intstead for the mob to rape. God doesn't care about this, but later turns Lot's wife into a pillar of salt only because she looked back at the city as they were leaving. Can't spin that one to make Yahweh look good no matter how thick those Holy Spirit glasses are!
Chapter 22: God commands Abraham to kill his only son Isaac to show his obedience. Of course the angel stops Abraham just in the nick of time. Christians think God was merciful for not having Abe go through with murdering his son. I wonder how Isaac felt about that.
Exodus: God sends plague after plague upon Egypt, even after Pharoah said he would let the slaves go. It was God who kept the slaves in Egypt as he "hardened Pharoah's heart" quite a few times after Pharoah consented. Most of the death could have been avoided when Pharoah first agreed. But apparently, Yahweh wasn't done killing.
Leviticus 26: God lists all the punishments for not doing what he says including "sending wild beasts among you, to rob you of your children" and "ye shall eat the flesh of your sons and the flesh of your daughters ye shall eat". He really seems to enjoy punishing innocent people, especially children, for something someone else did.
Numbers and Deuteronomy: With Yahweh's approval, the Israelites slaughter city after city, men, women, children and animals. Including the poor guy who picked up sticks on the sabbath. He also personally killed tens of thousands with fire, plague, venomous snakes and caused the earth to open up and swallow men, women and children (because the MEN were rebellious).
He also commands Moses to kill all the male Midianite children, all their women who were not virgins, but tells the Israelites they can keep all the virgins "for themselves". Overall, they ended up with 32,000 virgin girls and women.
Joshua: Yahweh helps Joshua slaughter everyone in Jerico, Ai, Makkedah, Libnah, Lachish, Eglon, Hebron, Debir, and the Gibeonites. At the Waters of Merom, God commanded Joshua to "hamstring their horses and burn their chariots."
And this interesting nugget:
Joshua 11:20 - For it was of the LORD to harden their hearts, that they should come against Israel in battle, that he might destroy them utterly, and that they might have no favour, but that he might destroy them, as the LORD commanded Moses.
That one certainly says alot.
Judges: More slaughter by the Israelites under God's command.
I Samuel: God kills 70 men for looking into the Ark of the Covenant. More men, women and children slaughtered by God's command.
II Samuel: Uzzah reaches out to steady the Ark when the oxen stumbles. God kills him for touching the Ark. More slaughter by David and his armies under God's command. God sends a plague on Israel that kills 70,000 innocent people to punish David for sinning.
2 Kings: Elisha curses 42 "little children" who made fun of his bald head. God sends 2 she-bears to kill the children.
God's punishment for Babylon:
Isaiah 13: 9 Behold, the day of the LORD cometh, cruel both with wrath and fierce anger, to lay the land desolate: and he shall destroy the sinners thereof out of it.
11 And I will punish the world for their evil, and the wicked for their iniquity; and I will cause the arrogancy of the proud to cease, and will lay low the haughtiness of the terrible.
15 Every one that is found shall be thrust through; and every one that is joined unto them shall fall by the sword.
16 Their children also shall be dashed to pieces before their eyes; their houses shall be spoiled, and their wives ravished.
18 Their bows also shall dash the young men to pieces; and they shall have no pity on the fruit of the womb; their eye shall not spare children.
Job 1 & 2: God allows Satan to kill Job's children, destroy everything he owns and curse him with boils to prove to Satan that Job would still worship and obey God even if God cursed him.
Hosea 13:16 Samaria shall become desolate; for she hath rebelled against her God: they shall fall by the sword: their infants shall be dashed in pieces, and their women with child shall be ripped up.
That is just a smattering of examples from the Old Testament that describe Yahweh's character. And I didn't even mention those immoral Mosaic laws! (other than the poor guy picking up sticks on the Sabbath). How much twisting of the scriptures does it take to make that god appear as one who loves all his creation "unconditionally" instead of the disgusting, immoral, genocidal, baby-killing, woman-hating, jealous, petty, murderous tyrant that is described in those books? How can a single drop of goodness be wrung from the fabric of Yahweh's character as the OT describes him? And yet, not only do Christians claim him as their god, they don't have a problem with any of the atrocities he commited. They see those horrible acts as good and moral because if God did it, it MUST be good and moral. And because of the Original Sin caveat, we apparently all deserve to be slaughtered if God sees fit because we can't possibly know his REAL reasons for doing those things and those things are automatically, unquestioningly righteous and just, because it's God. William Lane Craig said when God kills children, it's actually an act of love because they get to go straight to heaven. WHAT KIND OF WARPED MIND AGREES WITH THAT???!!!
It doesn't matter if the Old Testament doesn't apply to Christianity. Yahweh is still the Christians' God. They are still worshipping a character who makes Satan himself look like a Cub Scout. And they really don't see that?