The symbolism of the Cross is the two lines intersecting parallel: one, eternal life with "God", the other our "earthly" (corporeal) life that is temporal, mortal; where they intersect rests the "Christ", the living-and-dying God. All the symbols relate to you --together they are an image of "you," or more precisely the Christian philosophy as it relates humans to everything (the world).
Stripping "heaven" of literalism (concretized symbolism), I see a metaphoric image of eternity, of that "life" that, for Christianity, is expressed in terms set to contrast and parallel with the world-as-we-know-it, the "earthly existence." For some, like the Catholics, "that" life is more real and important than "this"; for others, like the Protestants, "this" life is more real and important than "that." Each acts according to his beliefs.
Both believe firmly in the divided world, the "mutually exclusive," the "n'ar the twain shall meet" --until death. Death eliminates the "this" leaving nothing but the "that."
The "Christ" to me rests at the intersection as a symbol of the recognition that "this" and "that" are "one", i.e. unity. Two worlds are one. At the risk of launching into lecture, we have many such "two worlds" that compose our paradigms of how we (humans) interact with everything (the world), many such divides: mind/matter, subject/object, inner/outer. The presence of a divide separates "us/me" from "other".