Because hell is not a happy place. If pagan thinks some pagan ritual directed to a non-existent pagan god is going to atone for his sins, he is sadly mistaken. If he is so far gone as to not even recognize sin, he is in even worse shape.
My impression is that God is not going to care whether I am an Episcopalian.
Yes, that is your impression. But that is not what God taught us when He was here. Jesus didn't come here to spread Indifferentism.
God gives us free will therefore he must respect what we do with it, given that we do not use it to harm others.
God respects our free will choices, by and large. He also went out of His way to let us know what it is He desires from us. And it is more than merely not harming others. We are to love God and love our neighbors. I fail to see how worshipping a false, non-esitent god, or no god at all is loving God.
Praying to Vishnu or Buddha does not harm others.
It leads others to conclude that these beings exist and are worthy of devotion, when we know that is not the case. This is harmful to the soul, especially the souls of the innocent.
SD
Then we are back to the original question. If paganism is so bad (according to you), why does God keep putting souls into babies that are going to be grow up as pagans?
But that is not what God taught us when He was here.
Given that we have about 200 different denominations, seems there's some disagreement as what exactly God taught. All scriptures were written by men. Not a single one was written by any divinity.