On what grounds would God be told that He can bring death to millions of people at the end of a normal life span, but that He may not do it in any other way?

The Church was not left in this world to perfume the dung-heap of fallen humanity, but to take out, one by one, those who will be saved from the coming destruction.

One of the consequences of sin is that it makes the sinner pity himself instead of causing him to turn to God. One of the first signs of new life is that the individual takes sides with God against himself.