Either the Garden of Eden Test Was a Sham or a Myth

In a previous post of mine I argued that the "supposed" test in the Garden of Eden was a sham. Then along comes my friend Dr. Dan Lambert who argued that we atheists have it wrong because "The Garden story is a myth invented to explain why people sin. Simple. End of story." At least Dan understands it for what it is. But if he's correct then how does this save his faith from refutation? Whether it's a sham test or a myth it doesn't matter. Why should any intelligent person base his faith on ancient myths? And there are lots of them in the Bible.