Jokes aside, here are my main reason Jesus existed:
- Jesus' disciples (and James) never became Christians (see http://historical-jesus.info/108.html
- At least one of Jesus' disciples offered his testimony (c/w with anecdotal material) about Jesus' ministry to the Markan community (see http://historical-jesus.info/20.html
- This Jesus was a "humble" poor Jew, with no divine power or origin (see http://historical-jesus.info/6.html
- This Markan Christian community, at the time the gospel was written, and in view of Jesus being elevated by Paul as a Divinity, was expecting Jesus, in his human phase, would have shown divine power and/or origin and not exhibited failures or objectionable conduct/sayings.
- "Mark" wanted to include bits and pieces of the testimony heard from eyewitness(es) in order to provide his gospel with an air of authenticity.
Then we have a dilemma:
- How can extraordinary things requiring divine intervention be added to a human Jesus and his story when the testimony about him did not include any?
- How to use Jesus' disciples when those did not have any reasons to embrace later Christian tenets (Jesus as resurrected & Christ, resurrections, meaning of the "passion", etc.)?
- How can failures or objectionable conduct/sayings (either from Jesus or his disciples) heard from the disciple(s) be cancelled?
But if my five points are correct, then we should find, in Mark's gospel, the author facing that dilemma and providing solutions. And here they are:
Solution 1: Disciples getting gag order from Jesus:
a) NOT saying Jairus' daughter was resurrected (5:43)
b) NOT claiming Jesus was Christ (8:30)
c) NOT telling about the events on the high mountain, which included transfiguration, God saying Jesus is his Son and Moses & Elijah alive in bodily forms (9:9-10)
Solution 2: Disciples being ignorant or kept in ignorance:
a) NOT aware of the (Christian) meaning of Jesus' future passion (8:33)
b) NOT understanding what "rising from the dead" meant (right after seeing Moses & Elijah!) (9:10)
c) NOT asking about the meaning of (among other things) Jesus' future rising (9:32b)
d) NOT told about the Empty Tomb (16:8)
Solution 3: Disciples being too dumb to notice extraordinary events:
a) NOT "seeing" the miraculous feeding(s) (6:52, 8:4, 17-21)
b) NOT considering "walking on the sea" or/and the following stoppage of the wind as divine miracle(s) (6:52)
Solution 4: Damage control on witnessed failure & objectionable conduct/saying:
a) Jairus' daughter not resurrected (damage control: 5:42).
b) Rejection of Jesus in his hometown and his failure to heal people there (damage control: 6:4, 5b).
c) Near-impossibility for wealthy to enter the Kingdom of God (damage control: 10:27).
d) Disturbance in the temple (damage control: 11:17).
e) Peter saying Jesus cursed at a fig tree which withered later (damage control: 11:22-25).
f) Disciples falling away after Jesus' arrest (damage control: 14:27b).
"Mark" had to contend with eyewitness' testimony which was not favorable to Christian beliefs then and he supplemented to this "lacking" testimony.
Note: in gMark, Jesus never declares to his disciples he is the Son of God.