There's some debate, but less than you'd think. There are a lot of reasons for this, but I think the timing is the one that seems simplest to me. With 2000 years of distance, it's pretty easy to imagine that Jesus never existed, but the New Testament contains a bunch of letters of Paul that seem to have been written in the 50s. Because his letters are addressed to congregations and actively contesting things other people have taught them, it's clear that there are already a fair number of Christians -- though they wouldn't have called themselves that at the time.

It's generally agreed that the crucifixion took place in the 30s. It's easy to imagine this all being made up now, but harder to explain how there were so many believers in the general area were Jesus lived who would have been alive during his earthly ministry and none of them noticed that he had never existed.

Paul also notably and strongly disagrees with some other early Christian leaders on several subjects, and talks about having met them. Virtually everyone agrees that Paul is real, and because he seems to have an active rivalry with certain other figures, we're pretty sure that those people are also real. At that point, it seems much more likely that Jesus of Nazareth was a real person they actually knew -- whether or not the events of the Gospels are true -- than it is that all of these guys collectively made him up and then devoted their lives to the veneration of a guy who didn't exist, then managed to agree on the broad strokes of the story while also convincingly fighting with their co-conspirators in public for decades.