Why do people disregard Evolution and natural selection?

I've heard a lot of people disregard evolution and natural selection, and ask, "if we came from apes, why are there apes"; it seems that these people do not understand that a species may branch off of another, like sharks and crocodiles. They suit their environment perfectly, which is why they are relatively unchanged, and why there are no croca-ducks; they would not suit their environments. I am a catholic, so don't give me the whole "you're disrespecting God by believing in evolution" thing.