if Darwinian evolution/natural selection is ever overthrown (I don't mean modified or expanded or altered, but completely discredited)
by some other scientific theory, it would make no difference to the creationists and independent design people. If it were replaced by some other scientific explanation of variation and adaption in living things, their major objection to it would still remain.

Darwin's contribution was, in a way, greater than Newton's. He was the first to show that the most complex and subtle of natural phenomena were capable of arising through simple mechanisms and processes that did not require conscious direction. In fact, they were inevitable. He did not prove that there was no god, what he proved was that god was not necessary.

This is why the opposition to Darwinism is so bitter, because it shows a case where god is not needed to explain it. Of course, religious people can believe in evolution, and evolutionists can be religious, but the people we are describing have drawn the line here. They don't stop at the creation, they see a world which demands the constant maintenance and management of a divine being, in every single detail and action. It is their perception of this world that makes god inevitable and self-evident, if that perception is threatened or questioned they have no other philosophical or intellectual basis for what they believe. They must have a constant, irrefutable, reason for a god in order to believe in him.

In short, they have no faith.