I think you could easily believe it if you wanted to. Belief is a choice, even when it's a passive choice.
Believe if I wanted to? Highly unlikely, IDK. I've tried attending an assortment of religious groups over the years, but I've never experienced a moment in which I uncritically just believed what I was being told. My brain simply doesn't work that way.
But wouldn't you say humankind in general has done things worthy of death?
The average person in the street? No. Absolutely not. A comparative handful of people, perhaps -- Serial killers, warlords and the like. I also think that any god worthy of the name would be able to come up with a more creative solution to deal with that troublesome handful more effectively.
So I don't think you need to construe his crucifixion so individually. Yes, it was for you, but not only for you.
How can I not take it personally? Allegedly I am to be condemned for not being able to believe it. And even if I don't personally warrant anything more than a kick in the shins, I'm not going to stand idly by and let someone else suffer the kick on My behalf.