Anyway, here goes. First, the basics. Blood atonement is Christians' attempt to explain why their god not just chose but also needed to sacrifice his only begotten son to wash away the sins of the world. Blood is necessary because their god's sense of justice is so high. Only most Christians are quick to add that, unlike Genesis 1:1 and so on, we must not take the word "world" (John 1:29) too literally because apparently the atonement works only for those who believe what various parcels of Christians insist that we all believe, exactly as they do. And, of course, we have to forget the painful logic that an all-sovereign, all-sufficient, and all-powerful god would probably not "need" to do anything he didn't already intend to do from the beginning--well, from before the beginning, to torture logic and language further.
The atonement is evident even in the Old Testament, say the Christians. It involves the sacrifice of something that bleeds--so, even in Moses' first book, God favors Abel's sacrifice of a lamb over Cain's vegan offering. More importantly, the thing that bleeds must be innocent and without blemish. To sacrifice something that by all ethical standards should not be put to death--the innocent--is precisely what the Judeo-Christian god demands as fulfillment of his sense of justice--a sense of justice well beyond our small human minds' ability to understand. Clueless mortals that we are, we tend to think of an innocent as precisely the one we would not want to kill--or have killed for our satisfaction.
At one point, evidently, children were a satisfactory option because, I assume, they had not yet lived long enough to be corrupted. (Christians vary on the point--often within themselves--of children's innocence: they are born into sin, which is why it's okay to scare the hell out of one's children to turn them towards the paths of righteousness, and they are born into sinless innocence, which is why it's not okay to let them watch R-rated movies. Nobody's very good at explaining the contradiction.) Of course we all know (or should know) that it's the pagan god Moloch who demanded the sacrifice of children--not the god of the Hebrews and later of the Christians. Moloch got a lot of bad press in the books of Leviticus, Second Kings, and Jeremiah, long before Allen Ginsberg singled him out as the god of the military-industrial complex.
However, if Moloch is the bad guy, explain this. It is Abraham's god who suggests to the "father of faith" that he should deliver up his son Isaac on an altar. See Genesis 22. As we're all told in Sunday school, this is just a "test" of Abraham's faith--but it's worth paying attention to the fact that Abraham neither balks nor regards the command as unusual--and this is only four chapters after Abraham begs till the cows come home to save the citizens of Sodom for the sake of ten or so righteous men. But about his own son, he doesn't say a peep. Had Abraham lacked faith when he pleaded for the lives in Sodom? Or was a son--specifically his favorite son, born of his and Sarah's old age--somehow less worth pleading for?
Ultimately, even the sacrifice of harmless innocents is not enough to satisfy this god's idea of perfect justice. The sacrifice must be human and entirely without sin--i.e. morally perfect--and as much god as man. This ideal and completely good man must die. Christ! He must not die like Socrates, drinking poison from a cup, and he cannot simply die of old age. He must die a brutal and bloody death--of the sort only the cinema of Mel Gibson can do justice to. If he dies--in just such a vicious and comfortless way--with his god and father's back turned on him the whole time--then the rest of us can have everlasting life and go to heaven after we shed this mortal body (still dying, as it turns out, no getting around that).
Well, some of us can have everlasting life--about 3% of the whole human population, according to some estimates, perhaps as few as 144,000, indeed a small "world." Very small. Hardly enough, it would seem to me, to warrant the death--and such a grisly death!--of a perfectly innocent god-slash-man. But, then, the Christian god is a good god, not one of the cheap phonies the Mesopotamians, Egyptians, Greeks, and Indians cobbled together out of their studies of nature. The Christian god won't hesitate to sacrifice his only begotten son--born miraculously without regard to rules of nature and norms of sexual partnership (keep in mind that Mary was purportedly about 15 years old in 0 B.C., which would constitute an age difference in Jesus's supposed parents of upwards of 13.75 billion years--Mary Kay Letourneau, eat your heart out!)--and for all the god's trouble, and it was reportedly the best he could do, we have fewer people going to heaven than presently living in poverty (~80%), the famously "blessed" poor (no numbers yet on the "meek").
So whether there's a god or no god, I cannot pretend to be an authority. But if the Christian god is the one and only--and if he is exactly as described by professed Christians (about 33% of the world population--perhaps 11 times the number actually "atoned")--and if this god is loving, holy, good, all-powerful, all-knowing, never-changing, though not exactly punctual (ouch, Harold Camping!)--I strongly suspect the atonement would not meet even FDA standards of efficacy--much less be all that impressive to me.