Evolution has been proven, therefore it's what I believe in. I have not seen a shred of proof for "creation". What helped convidence me was college. Biological Anthropology and Geology were pivotal. My eyes were opened like never before. The former basically laid out the progression of evolution. The skull formation, etc. THEN the next year I took Biology 1 and 2. Oh my God! If there ever was any doubt, I lost all of it there. The Bible (or any other religious book) doesn't hold a candle to many of the modern textbooks regarding the formation of life.
I'll admit that I don't know what exactly got the whole process started. The idea of transpermia is intriguing though.