There are a few wing nuts out there who reckon Jesus did not even exist. But this is rubbish. How can we know?
We can know this because there is a lot of controversy surrounding Jesus, and everyone has an opinion. But among those opinions are the opinions of scholars. Now scholars are not particularly special people, but their work is Peer Reviewed. that means they cannot just get away with saying made up rubbish. Many scholars that write about Jesus are not even Christians, some don't believe in the resurrection. Like everyone, they are biased, but they are biased in different ways. So considering all their different views, when they actually agree on certain things, those 'certain things' are pretty certain!
So what do they say? It isn't surprising that they have very different things to say about Jesus, but the controversies and disagreements are all around what Jesus actually said and did, not around if He existed. The idea that Jesus never existed is not believed by any credible scholars at all. Historians, Theologians, Philosophers, Scientists, Archeologists, Atheists (people who believe there is no God), Theists (People who believe there is a God) and Agnostics (People who are are not sure) all agree, Jesus clearly did live.
Now I disagree with informed Atheists particularly, and they disagree with me! But we do agree Jesus existed.
When to people fall out big time and have an argument, they argue over 'something real'. So one might accuse another of stealing their sandwich. The accused might argue back by saying "I don't even like chicken and mayo sarnies, I saw it and the smellmof it made me sick!"
When people argue like that, we can be sure there was a chicken and mayo sarnie! That's how it is with Jesus!
So, the fact that Scholars of all different biases, persuasions and opinions, different disciplines (fields of expertise such as history, Archeology, Psychology etc) all agree Jesus existed, then we have good reason to believe Jesus really did live. It's not the only reason, but it's good reason.
