jack

Jack is basically a sociopath. From the beginning of the story Jack displays an arrogant dominance over the others. He wants to be called buy his last name to stand out. He wants to be called Marridew because the other boys have "kids names". Jack is intent on gaining power at any cost. When he feels threatened he often reverts to violence (note the repeated stabbing of the trees!)Jack also becomes a master manipulator. He begins to understand what the boys fear and desire, and then he exploits them. In the end Jack not only delights in the pain of others, he seems bent on self-destruction. Although the burning of the entire island ironically saves them, it was most surely a sign of Jack's intent to destroy his enemy, his followers and himself.

and why did he make a new religion?

Simon didn't make a new religion. A Christ-figure is simply a character that holds some of the traits of Christ. Simon is otherwise an intense spiritual boy who prefers to be alone in nature rather than feel the stress of the boys.