Pascal's Wager: is it a legitimate argument?

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It is not; it doesn't prove anything. If it were an argument for any other religion or atheism somehow, it would also be invalid. It's called wishful thinking. If you believe in Christianity because of Pascal's Wager, then you're comparable to an old lady who buys a lottery ticket believing she will win definitely. Besides that, Pascal's Wager provides no information on your winning chances. Additionally, if you were a Christian and died while atheism was true, it means you have made useless efforts such as going to church and praying. If atheism held true, then what you wouldn't want to be doing is wasting your time; eighty years is quite limited in comparison to an eternity.

no because it disregards other religions and presents a duality between religion and atheism i dont know about atheism but most religions have differing requirements and stuff for the pathway to heaven

Going to church believing and such simply for the reason of going to heaven if such a place exists would probably get you thrown out anyway.