There is a mountain of evidence to support evolution. Also, not A does not imply B.
How could anyone believe in creationism? I can understand a general belief in God -- I don't share it, but I understand it. But a literal interpretation of the Bible that has been disproved by modern science? For goodness' sake, guys, bounds of reason.
Any evolutionists should watch the movie "God's not dead", it gives many good arguments in defense of creationism, such as that when God said "Let there be light", the big bang could have been the outcome.