Anon wrote:
'So all the millions of complexities, many interconnected, occurred by means of natural selection, beneficial mutations?'

Yes, maybe.

"How was insulin, inside the body, selected to metabolise glucose which is obtained from outside the body?"

Not a clue. Seems a silly idea though and not one which would be designed by anyone with thought for convenience.

"Has any atheist ever realised that without a guiding hand, evolution is impossible?"

Now this I find an interesting question. Actually it seems to me that it would be possible for a believer in a god figure to believe that their divinity had created life on earth, by evolution, and without giving precedence to any species.

Surely belief in a god does not have to include the belief that the creation myth as depicted in the Old Testament of the bible is a scientific description of the origin of man ('man' as in humans that is, we all know that the bible thinks that the origin of woman was a BAD BAD idea).