The elephant in the room that most religious people fail to acknowledge is the fact that they themselves deny the existence of any number of Gods. They actively disbelieve in hundreds of Gods whether they are aware of it or not. Ask any religious person today if they believe in the literal existence of the Egyptian Gods: Ra, Isis or Anubis; the Greek Gods: Zeus, Apollo or Hephaestus; or the Norse Gods: Thor, Freyr or Loki.
The answer will be 'no'. These Gods (you will be told) are not 'real' Gods – they are gods with a small 'g'. They are the simple beliefs of ancient people who wrongly believed in polytheism – and as we all know, there is only one real and true God, and He is my God.
But all of the above named Gods, together with their other fellow deities, were just as 'real' to the Egyptians, Greeks and Norse people as the monotheistic God of Christianity, Islam and Judaism is to those who believe today.
“I contend that we are both atheists. I just believe in one fewer god than you do. When you understand why you dismiss all the other possible gods, you will understand why I dismiss yours.” - Stephen Roberts