"BTW - allegory? based on what?"
Uh, that'd be the fossil record and the knowledge that the earth is about 4.5 billion years old. It wasn't created and populated with critters, including humans, in 6 days.
What evidence proves that the earth is about 4.5 billion years old?
Dr. Kurt Wise (Ph.D. in Geology)
http://www.answersingenesis.org/home/area/isd/wise.asp
Neither the fossil record nor the age of the Earth are proved to support an old Earth. Those statements are as much faith statements as your assertion that there is no God.