>>520354466 (OP)
In 321 AD Roman Emperor Constantine had a problem. On the one hand he has Christians, who were perpetually happy and upbeat about everything and telling people about how they didn't need to sacrifice chickens or babies and how you could live forever because God loves you.
On the other hand you had pagans who worshipped a Pantheon of degenerates who were constantly fucking and killing each other. They LITERALLY believed overt happiness was dangerous because the gods could get jealous and punsih you. So they clashed with Christians all the time out of fear.
So Emperor Constantine started what became the Roman Catholic Church merging Christianity with Pagan beliefs. This introduced ideas of eternal torturous damnation, hell, purgatory and conditional salvation. None of the early Christians believed these things. This was the original co-opting and subsequent monetization of Christianity. Some make the mistake of assuming this invalidates Christianity. It does not. It only invalidate Catholicism IMO.