Look, the title is pretty self explanatory but, the only reason Christianity became widespread is due to it becoming a religion favoured by the most powerful and widespread empire, the Roman empire. If you look at UK history, UK was a pagan place for a lot of history until the Romans invaded. It's quite a famous battle, dunno much about it tho, don't do history.
Similarly, the reason why it became widespread in other countries is mostly because of the British Empire as well as other Christian countries which invaded countries which weren't Christian and forcefully converted a portion of it. You can see that countries which were not invaded by Christian countries have a relatively low Christian population compared to countries which were invaded. For example, China, Taiwan, Indonesia, etc.
This is similar to how Islam spread to parts of the world, they spread by conquest and not through choice. You can see that neither of these religions are unique either, if you search up on the topic. For Christianity, Jesus is not the only one who has been worshipped as the Messiah, there are a lot of others, some are even worshipped today in parts of the Middle East. The story of Jesus is not unique either, it's been around for longer than when Jesus apparantly was born and died. This is one of the reason why some historians wonder if Jesus was actually a person, his story, or stories similar to his, has been around for longer than he has been.
I'm thinking of Korean Jesus in particular, however I lived in India for some time but never saw Indian Jesus.
Just a thought
By that logic, I would expect China to have started their first space program while we were still busy burning witches...
Edit: You all probably know what I'm talking about, but I should add that by Christianity, I meant the Catholic church/inquisition during middle-ages in Europe (the time of "heretics" burning and destroying everything that didn't agree with the general doctrine, aka anything that could have been a scientific breakthrough)