Claim. Life on earth is a brief training course whose entire purpose is to prepare us for eternal life in the spirit world; victory there is impossible without victory here.
Elaboration. “We must cross over from evil to goodness. The complete victory of our body means that even Satan has been completely uprooted and subjugated. We can go to heaven only after subjugating Satan. We cannot conquer Satan without a physical body. This is because the mishap that befell our body occurred on earth and consequently must be remedied on earth” (4.1. Life on earth is to prepare us for life in the spirit world, 65-293, 1973.2). The eighty-year span is “limited” but “our stage is the altar of the world.” Life is a “period of training during which we undergo a course that prepares us to acquire a universal personality” (ibid, 147-188, 1986.9.21); “a lifetime is but a fleeting moment compared to the eternal life after death” (ibid, 140-121, 1986.2.9). The Fall was committed in the body, so the body is the indispensable site of its undoing — disembodied piety cannot finish the work.
See also. csg-earth-and-spirit-world-form-one-dual-structure