Why does there need to be physical sacrifice?
I didn't read the whole article WW posted. The beginning seemed good, but it just went on and on, and I don't have the time to read the whole thing right now. I will attempt, to the best of my ability, to give a short answer to what is, IMO, a very deep question.
The first premise is basically what I saw in the first part of that article: That God is both 100% good and 100% just. Whether you buy that or not, that's the premise a Christian approaches this question from. The article cites a ton of Biblical passages on the subject, so I won't waste time trying to support it.
Second, sin as bad. Any sin. It is what separated Adam and Eve from God and got them kicked out of the garden. It is what separates man from God today. (Isa 59:2 ("But your iniquities have separated you from your God; And your sins have hidden His face from you, So that He will not hear.")) Its inescapable result of all sin is physical and spiritual death. (Rom 6:23) The natural question at this point in time for the nonbeliever (and, sometimes, for the believer as well) is probably something along the lines of, "But why? I don't see what is so objectively bad about at least some 'sins' that the outcome could or should be death. Why is
all sin supposedly so bad to a being who is so powerful that he should just be above it all?" And that's a hard one to answer, and I don't know that I
can give a satisfactory answer. I just understand that it is. I liken it to a situation I think most of us can probably relate to. I think of times when I've done something that for the life of me, I either don't see what's wrong with it, or I just don't see it as really all that bad. My wife, or my mom, or whoever the person on the other end of the thing, however, is mortally offended and thinks it's just the worst thing ever. Sometimes, if I want to reconcile with them, I just have to accept that I don't have the same perspective they have and it does me no good to try to justify myself to them because I just I'm not seeing the situation the same way they are. IMO, this situation isn't all
that different. If I accept that I am much more limited as a human being than a being who created every subatomic particle in the universe and the laws that have them working together the way they do, simply by speaking them into existence, then I can accept that he may look at morality in a way I'm not really capable of understanding in much depth. So, again, premise #2 is that sin is bad--really bad--even when it is something that looks relatively harmless to me in my limited mortal understanding.
Third, because sin is so bad, the only way to pay for it is by blood. Again, it is so bad, it requires death. The sacrifices in the OT are meant to illustrate this graphically. The sheer number of animals that had to be sacrifices on a routine basis by the Israelites is astounding. And that practice continued for a LONG time before Jesus. I've often thought to myself that it's the "Lord of the Rings effect," in a way. Don't get me wrong--I love the LOTR stories. But boiled down to their simplest essence, it's a REALLY long story about some guys on a LONG walk. A lot of novelists have told great stories about incredible questions and had great character development in much shorter works than the LOTR stories. However, IMO, part of what makes you feel the weight of the journey and the complete transformation of the characters is the sheer length of narrative. You can't read something that long and not have certain emotions and thoughts impressed upon you. IMO, it's similar to the Hebrew history, in a way. It was a long history of having to offer sacrifices to impress upon us that literally TONS of blood was shed over an astounding period of time to temporarily attone for sins.
That brings us to the conclusion where we are told that to satisfy that price, Jesus had to become physical flesh and blood, live a perfect, sinless life, and become that sacrificial lamb to attone for all sins, past, present, and future, once and for all. What that means for each individual on this earth is this: God says He expects X of us as His creation, and the promise is that if we follow the instructions, we are promised a reward. However, if we sin and fall short of keeping those instructions, there is a penalty to pay that, again, is the ultimate steep penalty, whether we understand why or not. The only way to have the sentence of death acquitted is by that sacrifice, and that is what makes the sacrifice admirable: I'm on spiritual death row, and the sentence
will be carried out. I'm a dead man walking, and if someone else chooses to pay that penalty in my place, I literally owe them my life.
Again, I'm not expecting you to buy what I've said. I think you've made your position clear. But hopefully, that at least explains it. Probably not the best explanation, but it's the best I can give at the moment.