Two immortal beings, the Sphinx and the first vampire Varnae, observed Jesus during the time he was alive. In Immortal X-Men #1, Exodus implies that Jesus was a mutant, despite having no proof or any way of knowing Jesus' actual status.

Is Jesus a Marvel character?

Jesus is a Marvel Comics character and ties in with Marvel continuity.

Who is the mutant God?

Through the personality of The Legion (the name given to Personality #5, which claims to be Legion's "real me"), he can warp time and reality. Magik nicknamed this personality the "God-Mutant."