Over 3700 documented deities since the Sumarians, prior to that who knows? Of those 3700 at least 2400 are identified as gods or goddesses.Arguing apples (beliefs=religion) with oranges (facts=science) will never answer the problem. It's a categorical mistake. You'll just go round 'n round trying to convince a believer with facts or trying to dispel facts with beliefs.
With that said, I think the more interesting question is if there is a deity, to which religion does it belong? Hindu? Islam? Inca? Christian? etc. There must be hundreds of religious deities each with their own unique sacred and infallible religious texts (the bible, Quran, etc). One would think you'd better have chosen the right one or face the consequences. So what makes one religion the correct one and the others not?
And we can also break that down into branches of a particular religion, take christianity for example with of 37000 different cults. Each claiming theirs is the only way and most claiming that unless you are of their cult you will not get to heaven.
As to what makes a religion (or a cult) the right one, well of course it all depends which one the particular believer belongs to, that is obviously the correct one.