Well I guess the prime question is how do you know Jesus even existed? There are no contemporary to Jesus accounts of him ever having existed by either his followers or the general population. The first writings about Jesus came some 37-38 years after his death by people who were born after his death.
Let's see if I can give you a reasonable argument (that is the correct use of apologetics, making my faith reasonable, though not proven, right?)
Let me build it logically. We have the ability to imagine worlds that do not exist, and to work in them (as in fiction and videogames). We also have knowledge whose validity is not guaranteed in the world (2+2=4 for example, but if you take your money and count it, the government takes some away, so the equation might not be valid.) There is no evolutionary reason for us to have either of these, no survival value; they serve no purpose in the world itself. Next, we have a sense of "better". This sense seems particular to humans, so it seems not to fit a random world as well. For all these reasons, it is reasonable to believe in some force external to the universe giving it meaning that we can sense. (Again, not proved, just explained why.)
There are many people who feel this way, and many approaches, systems or paradigms to how to respond to this force. One is the belief that this force is, in fact, a person, and has communicated with us at various times and places. i accpet this one for reasons I will state. Further, I accept that a person, Jesus, lived on earth, as His personal emissary, in fact His son, and taught, acted, and died in a way that might bring us closer to God. This is what we call Christianity.
Okay, why this one approach, and not the many others? In math, some answers are closer than others. 2+2=5 is less wrong than 2+2=1000. I believe it is the same here. Christianity offers me several things that the other approaches do not. Freedom to be fully me, assurances that I am loved, personal experiences, happy eternity, etc. Many of these, but not all are offered by other systems. But here is the decider: Christianity is the only religion containing any promise beyond earthly life that offers proof of what it says that works now in this life.
We cannot prove the Bible is anymore than a fictional story with some archeology here and there. We cannot prove Jesus ever lived. We cannot prove He died. That He rose. That He ascended. But we
can prove that He is at the right hand of the Father right now, interceding for us. If the other things were not true, that could not be true, because all these things we cannot prove must happen in the order I gave, before the last can occur. If I can prove the last, I prove the entire chain that led up to it, from Genesis 1:1 up to and including the ascension and His position in heaven now.
So how do I prove his position? Because it works. I have learned through experience and teaching to apply and share the life what I believe has taught me. Every day, I see person after person who will follow what I know, be set free from guilt, empowered to love and serve, given new purpose and hope. There is no other explanation possible. This does not happen in Islam, witchcraft, Buddhism, of any other system you care to name. Any of those systems requires performance of certain actions and thoughts. Christianity requires only cooperative reception of what we call grace. Something must be getting that grace from outside the visible world, because we do not do anything to get it for ourselves, it seems to come from nowhere, and that is exactly what Jesus said He will do (if the Bible is true) is have the Father give us that grace, and the Father is our name for that force.
I believe what I believe, because it resonates in the human heart, and fills human longing like nothing else. It's the 4 to the 2+2 when everyone else is saying 5, or 6, or 1000.
