Normally, if we talk about evolution, it's something that is difficult for them to comprehend. It took me quite sometimes even after I had turned agnostic until I admit evolution is true.
Evolutionary theory aside, the order of first appearances found in the fossil record contradicts Biblical creationism, which teaches that all life forms, including humans, appeared at once, with no ancestral species preceding them. Were we to find mammals appearing before invertebrates, or reptiles appearing before amphibians, then that might be evidence of supernatural creation.
I've had some fundamentalists tell me that the fossil record was manipulated by Satan to make it look as if life evolved.
Of course, if one accepts that life evolved, then it follows that we exist unplanned...