Superman was made by two Jewish guys. I doubt they would have based it on Jesus in anyway.
Because a person is of one religion (or none) doesn't mean they can't borrow elements from other faiths in their storytelling, particularly when you're dealing with a cultural myth as pervasive as the story of Christ. Besides, the Messiah is
a Jewish story - they only differ from Christians as to whether or not it's happened yet.
Fictitiously yours, Trent Roman