I mean, scientifically this is a hypothesis that there is no way of proving. It’s theoretically possible there is a god or gods that whispered in someone’s ear to set up a particular religion and would do the same again if all the religions are wiped out. Competing religions doesn’t disprove that, it would just mean those people didn’t hear the whisper (or maybe misunderstood it). This statement is literally impossible to prove or disprove (without lots of genocide and record destroying).
If we’re gonna base ourselves on science, we should actually follow its rules.