>what if he tricked everyone
This is the nugnostic-nihilistic argument.
A more reasonable argument was presented in neognosticism by C. Jung. And expound on further in the game Fear & Hunger.
>What if Christ split off his personality into two separate figures?
The idea is that christ, in trying to become perfect, split his personality in two.
One being the Ego ideal- the perfect and pure christ.
The second being his shadow.
>what is the shadow?
The shadow is everything stored in the unconscious, especially those things which do not accord with the ego ideal.
Where does this split begin? If we take any of the gnostic scriptures seriously, we see that christ is a very dionysian figure as a child. He blinds and maims people for small insult as easily as he blesses.
We may locate that the split in personality begins in his 40 days in the desert. Christ in his attempt to purify himself dueing a meditative period of intense fasting/prayer, encounters his shadow side, manifest as the devil.
To progress, one must absorb the shadow and transcend the ego ideal..but christ did not do this. Christ instead banished his Shadow as an ultimate enemy.
The moment Jesus did this, his personality then fractured and he became two beings.
Satan & Christ.
The crux of this theory is that Jesus, by rejecting everything that went against his ideal ego, created Satan and became two people. Satan is Jesus's darker and more vengeful impulses.
But it goes further yet- this means even, that Christianity is an unstable religion. Manifesting either as Christ's ego ideal of the perfect, omniscient wisdom of the God of light. Or it becomes the hateful and radical wrath of a powerful god of the world.