[Agema]

Mainstream interpretation of the Bible, even since the earliest Christian theologians, has never been that it is entirely literal.

Even if the Bible is the word of God, it does not mean it has to be literal truth. It is logically consistent to say that although God is perfect, any communication he could render to humans must be interpreted by imperfect human understanding. (That argument was originally based on Platonic philosophy, although it's also compatible into one of the major strands of postmodern philosophy.)

The failing with literal interpretation was pointed out over 1500 years ago by Christian theologians. They noticed their understanding was far greater than the primitives who wrote the early Bible and had even less chance of comprehending the whole truth. As human knowledge grows, Christians need to consider whether tracts of the Bible are actually loose framework, grossly simplified versions of events, or outright allegory.

For Christians to back total literal interpretation is to put them at odds with the intellectual background of their own religion. For atheists to do it (assuming they aren't countering a literalist), it's nothing but setting up a straw man.