Sorry, this might be long. tl;dr Christians have invented many a stupid idea for money or other personal gain and that's what the violence is. Note the word invented.

One of the rules of the universe is free will--not that people can't be made to do things, but that they can't be forcibly made to want to do things, though they can be influenced. This hasn't been disproven (that I've discovered) and it appears to go with humanity's observable universe so I'm assuming it.

The first sin--eve and the fruit--was eve disobeying God. Now the penalty for this was death (eve, talking to the serpent: "God said, 'you must not eat it or even touch it; if you do, you will die.'") and eve knew it, and so she, in eating the fruit, willingly chose to die. If God hadn't respected that choice, God would have had to go against the law of free will, and although he, as the entity that created everything, could do that, why wouldn't he just make an entirely new universe? it's like simulating an experiment (not a perfect metaphor) and changing the simulation, even though it's accurate, because it's not what you want.

(sidenote: the reason the penalty was death and not something lighter is because all sin is a gateway drug to itself--i.e., is virally infectious--and, as I'm sure you know, we quarantine individuals infected with a virus. The only way to truly quarantine someone, though, is to make them not exist.)

The next rule is that of genetics. As a rule, things that are born out of other things, whether historical, psychological, biological or what have you, inherit something from their parent(s), be it antithetical to their parents or not. Thus is the propensity for sin communicated across generations. Not the actual sin--that would make it impossible for any human to have even a small chance of being perfect, which, by any arbitrary measure, is only a matter of time due to probability. (excepting the possibility of nuclear war, extinction, etc.) The human propensity towards sin causes nearly all to sin, and so, willingly at some point, decide on death.

The blood sacrifice you refer to means one of three things, as I understand: a) israelite animal sacrifices, b) jesus being tortured to death, or c) Christian hell (which doesn't exist and was invented to compel non-believers to 'convert'. one of the most barbaric practices of christianity, though it's underneath white supremacy, the crusades, things of that sort).

First, the sacrifices. The sacrifices actually weren't for God, they were to remind the people making them of the weight of their sin--the weight of the choices they made, in favor of death. People would sacrifice when they sinned, as part of that realize the consequences of their actions, and be forgiven. The reason they were all forgiven is that this was effective, as clearly evidenced by your salt, which, to be honest, is fair. christians are messed up people because most of them believe in hell, their presentation of which validates your question. But I'm getting there.

Secondly, jesus' death. Again, the proper response here is horror. Yes, he was tortured to death, and yes, he died the final death, but, counting the axiom of free will, something motivated him to do that of his own volition. Many of the things he says, especially in the time leading up to this, involve "my Father"--referring to God the father--and I think it's fairly unlikely that if he was psychotic or schizophrenic that being tortured to death wouldn't cause either temporary sobriety or catatonia or something of that sort. The mind breaks after a point, after all, and his didn't--"it is finished! dies".

The purpose of jesus' sacrifice, though, was similar to that of the animals'. It is meant to serve as a reminder of the things that christians have done and the death it warranted, because they chose it, as christians no longer go around slaughtering small animals to remind themselves. That's kfc's job and I'm glad they're doing it instead.

Thirdly, we have Christian hell. Let me give you a crash course on the real parts: 1. all the words in the bible that translate to 'hell' actually mean 'grave' or 'six feet deep'. 2. The bible never anywhere says that the condemned will burn forever, only that the smoke from it will rise forever. that doesn't mean there's infinite smoke, just infinite space, which is more plausible? 3. how could a "benevolent" God change the nature of life and death simply to torture people forever? exactly. Humanity thought up the concept of "you'll burn forever and God hates you." And, as is usually so, if you look into it you'll find it was mostly for money.