That's true, there are alternative explanations. I spoke of a "decisive refutation" here and I certainly stand by that, though, because we must assess which explanation is best. I recently wrote a criticism of some arguments by the Catholic philosopher Peter Kreeft, which goes into CS Lewis's "argument from the desire for God."

It's possible that God implanted in us a way for us to access or to know him. But is that explanation better than the naturalistic one? I think not.

The theistic explanation of the natural origins of religion isn't just ad hoc; it makes God superfluous. Plus, it succumbs to Occam's razor. Plus, it's implausible because God also supposedly reveals himself directly in the form of mystical theophanies. Why would God go to the trouble of implanting a flawed antenna that separates the nations more than it unites them (since the idea of God splits into various religions and tribes), when God could override everything and reveal himself more directly, through an angel or whatever? "Ad hoc" is an understatement.