I think you are seeing this a little too 2d. The reason the Christian meme spread so well is more complex than that. A codified belief system written down, the thought of a God that loves and cares about you, a path to redemption and forgiveness for sin or mistakes, these are just some of the reasons that it has been so successful. It wasn’t always just forced on people although there was that too. It’s just a really good meme and great story when you get to the heart of it. The people meeting in secret when Christianity started and risking their life to do so weren’t forced into it at all. Like capitalism, Christianity fits a lot of human needs and desires that are hard coded in humans.
There definitely was a moment when Christianity was a secretive cult ostensibly fuelled by brotherly love, but certainly by the time of Constantine it had become a major political force.
My impression is that Christianity took over Europe more for political reasons than the good story. There were strong incentives for pagan rulers to "convert", and force it onto the populace.
I agree that the good story is key to its staying power.
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> Christianity fits a lot of human needs and desires that are hard coded in humans.
Which version are you talking about because there is no one definition, Christians cant even agree amongst themselves about Christianity. Anyone is free to make up their own religion, include the bible in the lore, and call it "Christian".