The Spirits' Book
Book Two - The Spirit World
Chapter II - Incarnation of Spirits
Purpose of Incarnation
132. What is the purpose of spirit incarnation?
“God imposes incarnation as a tool to reach perfection. For some it is a means of making amends, while for others it is a mission. Every spirit must experience the difficulties of physical existence to reach perfection, therein lies their atonement. Incarnation also requires a spirit to contribute to the work of creation. To fulfill this purpose, spirits assume physical bodies in harmony with the material state of each world to accomplish the missions that have been appointed to them by God. Through these missions they contribute to the general good while also achieving their own advancement.”
The action of physical beings is necessary to the operation of the universe, but God has wisely designed this action to serve as a means of climbing closer to God. Thus, through the law of providence, all things are connected and everything in nature is united.