The Cross, Golgotha, Pharisees, Salvation, Judas, Christ, all-important elements of the Bible, with lots of psychological weight. This is why John Knowles uses Biblical symbolism so heavily in his book, A Separate Peace. In the book, the tree from which the boys jump represents the "tree" on which Christ was crucified. Gene represents Judas and Finny represents Christ.
Finny, the central character of the book, symbolizes Jesus in a number of ways. First, he had to die. It was predestined from the beginning. Just as Christ was without sin, and therefore the perfect saviour, Finny is without corruption from the war (which represents sin) and therefore a perfect saviour from war. He saves the boys by playing games with them, such as his favourite, blitzball, which shows them the futility of war. In the book Gene says that Finny would probably try to play games with the soldiers on the other side if he were in the war. This is similar to the way Christ greeted all sinners with his message of peace and salvation. And when Finny is pushed from the tree he symbolically dies and carries the sin of war away for the other boys.
Just as Finny symbolizes Christ, so Gene symbolizes Judas, the betrayer of Christ. He betrays Finny by pushing him out of the tree. In the Bible, Judas sells Christ to the Pharisees for thirty pieces of silver. In the book, Gene's mind represents the Pharisees in that it tells him that in order to obtain glory in the school, thirty pieces of silver, he must betray Finny. But just as Judas threw the money back into the temple after the deed was done and hung himself (from a tree, ironically enough), Gene throws away any hopes of glory (thereby metaphorically "throwing the silver into the temple")when he lets his schoolwork start slipping after the accident and starts managing crew rather than excelling at a sport. He then joins the war after school. In doing this he "kills himself" by giving up to the great sin of war (In the bible, sin and death are almost always the same thing in that sin equals spiritual death.
