What makes you think there can only be one? I thought there was one santa claus, for years, until I found out that it was made up. Why can't there be many Gods, you have no proof to suggest there is only one, apart from some scriptures and a strong feeling that makes you feel good.
I am not saying you are wrong, I am just struggling to come to grip with the fact that one can only believe in one God, if millions of people believe different things, one can only assume that somebody get's it wrong. Are you not better off believing everything what is out there, until proven wrong? Why discredit all those other religions....
The fact is, humans have shown to be able to belief in anything whether it is bogus or truth.
Only facts can prove a belief system wrong.
And unfortunately facts quite often turn out to be estimations of the truth.
Look at the Greek and Roman Gods, fighting each other. In order for there to be more than one God they would have to be identical, a God being perfect in every way. Then they would fight, but you would not be able to identify one from another. It simply doesn't make sense.
We can all try to apply human logic and draw a conclusion on that, but they are all but assumptions at best, waiting to be overthrown by future assumptions. That is how it went and so it will always be.
There is no way of telling you are right in assuming Christianity is the one and only true religion. On that note I personally can’t see any reason to discard any other religion until proven wrong.
There is to much proof of people capable of believing anything in the right circumstance. Why put your eggs in one basket 😜