Looking past the awfulness of an all-powerful God allowing his son to be sacrificed for something that he himself caused, is pretty immoral.
And as you wrote, he rose 3 days later, it's like having a rough weekend.
And if one is in support of the trinity it becomes slightly more strange, as it is basically God himself, so it is not even all that impressive to be honest.
But if one completely removes the "he died" then there is nothing to it at all, so at least to me, a Christian would have to make the argument that he died to give the sacrifice some sort of meaning, because again it is already hanging in a very thin thread in so many ways.
Anyway, the purpose was not to argue against it, simply to give my answer to the question the OP had about it.