My pet theory is what I call 'The Hitch Effect' - I think Jesus Christ probably DID exist - actually the figure might be based on two or even more real people (*see end note) & he [or perhaps "they"] were a wandering Rabbi who gained some notoriety around the first century & the authorities didn't trust him so they nailed him up & that was the end of him. - But not in every sense...
Those who loved & respected him wouldn't let his 'spirit' die & would deny he is gone for good by saying 'He lives!' i.e. Lives on in their heart, but over the intervening decades before the New Testament gospels were written the Jesus story evolved from a mere metaphorical resurrection of his teachings to a myth that he himself physically not spiritually conquered death by resurrecting & this was a very powerful image which spread like wild fire among a downtrodden population of Jews in the Middle East back then.
The story also suited the powers that be because Jesus never said a single word against the inhumanity of life long ownership of people as personal property so they were very happy to see this 'meek shall inherit the Earth' philosophy promoted as well as the poor too. (This explains why even today the Chinese government are perfectly happy to see Christianity become popular as it keeps people docile by choice!) So it's a double whammy: The poor buy into the sop offered as a promise of a better life AFTER death & the rich & powerful love this idea because it suggests God says we should all be happy being slaves (& no where does the Buy Bull say a word against slavery - quite the opposite actually!)
So where does Hitch (Christopher Hitchens) fit in with all of this? Well Hitch was as you probably know, a very vocal anti-theist & a bit like Jesus, was much loved while he walked the Earth, He too was taken away from us far too early & so his wisdom [slightly lacking sometimes in my humble opinion] has also 'lived on' in many many quotes via the internet just as Jesus's quotes have via the gospels.
Now in the 21st century people tend not to interpret supernatural claims as out & out truths but back in the first century many people did & contrary to popular belief did so a lot of the time. People back then had no video footage & journalism to refer to & they actually didn't particularly care if a story was literally true only that it was a 'good yarn' i.e. A moving account which as far as they were concerned was as good as the real thing if there's no way to really know what's true or legend anyway. So Christianity grew from the same mentality that people like me & perhaps you too reflect - Keeping the word alive. Personally I love to quote Hitch again & again because he too was a skilled orator so I wan't to keep his 'spirit' alive but not by suggesting anything supernatural has happened.
Christians however do (or did back in the day) therefore they consciously or unconsciously concocted 'The Greatest Story Ever Told' & in a sense perhaps it is in as much that it's one story which so far has caught on with great success (32% of the world is some form of Christian).
Now tell me what YOU think probably / possibly happened about 2000 years ago.
YEAH, I DO!! In the USA, It's because the American Indian was massacred. OMG...,,.they were wiped out....by Christians. Don't you remember? Indians are heathens, no souls!!
Richard Dawkins' meme replication comes to mind.
Actually ,I believe christian beliefs are in decline and Islam is the growing religion for some reason.I really cannot explain the latter other than the Catholics with all of their scandals have lost many members.As for Christ, there were many saviors going around at that time. It was a good job just like today. People liked stories as they did not have much entertainment going on.They did not have the education also so it was easy to create these religious belief systems.
Take the Pew report link I sent. It shows that, in fact, Islam is the growing religion world-wide.
It is people, like us, that are the main reason Christianity is in decline and that the evangelicals are so desperate to push their agenda.
Whether Yeshua (Jesus) existed is irrelevant to me, because any historical figure is surely divorced from the biblical figure entirely. We do know that Paul (née Saul) existed and, for political purposes spread the "word" of Jesus, which led to the writing of the Gospels. Paul enlisted the help of one James who claimed to be Jesus's brother, lending credence to the story. Kinship claims are sometimes difficult to confirm today, to say nothing of a time when records weren't easily referenced, so it's not clear to me that James was actually Jesus's brother. The religion spread, but didn't get so big until Rome adopted it as the official state religion. From there, there was a massive marketing campaign that succeeded largely through co-opting pagan festivals for Christian holidays, and, once big enough, through intimidation and force, torturing and murdering the unbelievers.
My take is a combination of historical accident, and as Silvereyes said the best sales pitch and marketing plan.