Evolution does not equate to atheism. Evolution only disproves a literal interpretation of the Genesis account.
I think the word agnostic is useless because it does not really distinguish anyone as being different from anyone. Everyone is agnostic. No one knows that a God exists. Everyone is without knowledge - agnostic - of God's existence. The difference between atheists and theists is about belief - not knowledge. Theists believe a god exists. Atheists lack belief in a god. But both atheist and theists lack knowledge of God's existence - they're both agnostic, if theists are honest with themselves. So the word agnostic applies to everyone in the set of humans so it is pretty much a useless, superfluous word, being misused for political window dressing.