I spent a long time really pissed about religion in general, and really vocal about it, too. I don't regret that; I came by it honestly, and I'll bet you did too. There's a joke Aleister Crowley told I saw quoted by Alan Moore somewhere that convinced me to be more cautious about when I spoke up

There is the story of the American in the train who saw another American carrying a basket of unusual shape. His curiosity mastered him, and he leant across and said: "Say, stranger, what you got in that bag?" The other, lantern-jawed and taciturn, replied: "mongoose". The first man was rather baffled, as he had never heard of a mongoose. After a pause he pursued, at the risk of a rebuff: "But say, what is a Mongoose?" "Mongoose eats snakes", replied the other. This was another poser, but he pursued: "What in hell do you want a Mongoose for?" "Well, you see", said the second man (in a confidential whisper) "my brother sees snakes". The first man was more puzzled than ever; but after a long think, he continued rather pathetically: "But say, them ain't real snakes". "Sure", said the man with the basket, "but this Mongoose ain't real either".

If an imaginary mongoose is what someone needs, I don't think it's fair to fault them. Of course some religions give people imaginary snakes instead, and those deserve your anger, but it's not obvious which is which from the outside. Better to let it go until it's being inflicted on people who didn't opt in.