From New World Encyclopedia
Unification Aspects:

Polygamy is the partnering of a man (or woman) with multiple spouses. Although this is common in nature in many species, human relationships are more complex, and the families formed through sexual partnerships last throughout their lives, even into eternity. The human spirit is deeply affected by the sexual connection, the most intimate of human relationships. The result of sexual relationship is the birth of a child, the continuation of the lineage. The Divine Principle explains that the first human ancestors abused their sexuality, indulging in premature sexual activity without God's blessing, and that this is the origin of all human suffering. As descendants of the original false couple, we all exist in a fallen lineage that is separated from God.

The solution to our problems, therefore, lies in the correct attitude toward our sexuality, and the proper use of our sexual organs. Reverend Moon has warned that our sexual organs belong to our spouse, the person with whom we commit ourselves to a unique, exclusive, and eternal true love relationship. In his words, we should have "no spare key:"

A wife's reproductive organ belongs to her husband, and a husband's belongs to his wife. In this circumstance, a person's reproductive organ can be unlocked by one key and one key only. Under no circumstances should you make a spare key. This absolutely cannot be permitted. The wrongful use of this key leads to the destruction of the family and the nation. (Moon, Sun Myung. "God Is our King and True Parent" Harlem, New York, May 8, 2001)

Polygamy means that we provide many copies of our key, allowing several partners to unlock the holiest aspect of our being. God can never accept polygamous relationships as true. Although the Bible, and other scriptures, record the multiple marriages or concubines of key figures in God's providence, the best of these can be understood as necessary evils in the course of restoration; the rest as tragic errors.

Although many forms of marriage relationships have existed in the history of restoration, the ideal is where one woman is in partnership with one man. Together they can represent the qualities of the Divine. There is no need in the ideal for multiple partners, and children should receive love from two parents, the father and mother. Although circumstances have often been far from ideal, leading to multiple partnerships, polygamy cannot represent an ideal relationship for anyone.

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teachers and researchers who wish to further pursue these topics from a unification perspective.