Reincarnation is the story of physical and spiritual evolution. The plan for the soul was a cycle of experiences in the solar system in which the new individual would come to know creation in all its aspects, at the discretion of will. The cycle would be completed when the desire of will was no longer different from the thought of God. The consciousness of the new individual would then merge with its spiritual consciousness of identity with God, and the soul would return to its source as the companion it was intended to be.
The earth is an expression of divine mind with its own laws, its own plan, its own evolution. The law of karma, the law revealed to the ancient Hebrews, is the law of cause and effect, an eye for an eye, a tooth for a tooth. Unpaid debts (sins) incurred in the flesh must be met in the flesh, and reincarnation is the result. This same law not only applies to individuals, but also to groups of people as they act together. There is karma for families, for tribes, for races, for nations. When the souls who committed a war in a previous lifetime reincarnate to a nation for a new lifetime, a war will be committed upon that nation. Only when victory is dispensed by a nation with justice and mercy, will the karma of war be lifted from them.
Every person's life is shaped to some extent by karma: his own, that of his associates and loved ones, that of his nation and race, and that of the world itself. It is what the person does about these influences and urges, how he reacts to them, that makes a difference in his soul development. Because of karma some things are more probable than others, but so long as one is free in God anything is possible.
Thus free will and predestination coexist in a person. His past experiences limit him in probability, and incline him in certain directions, but free will from God can always draw the sword from the stone.
This law of karma, of reincarnation, was superceded by a new and greater law brought by Christ. This is the law of grace which frees souls from the consequences of karma and thus, reincarnation.