How would we know?

So in religious text we only heard gods voice. It never had a definitive sound, i.e male female. Some say it sounded like a man because it sounded like a voice they knew which was a man. So if e.t's came here and kept themsleves cloaked they could present a voice and 1, some, or all of us could hear it and then they could claim to be "god". So they could then say anything and the religious people would believe it and buy into it and do whatever that voice says. Let the name calling towards me begin