The flow of logic of the argument is this:

1. Marriage, by its nature and history, is exclusively a binding of men and women.

2. In the U.S.A. (and we are only debating American marriages, since other countries have different morals, customs and contracts, bringing in these marriages would make our discussion unwieldy) a necessary cause, though not sufficient cause, of marriage is one man wedding one woman.

3. This necessary cause arises out of religious convictions that have informed morality in the area of marriages; (e.g., though the Book of Mormon, the Bible and the Qur’an all call for marriage to be between a man and a woman, or multiple women, but never between two men).

4. Because religion excludes homosexual marriages, and as stated, marriage contracts arise from the religious institutions, marriages are by their nature extensions of religious institutions.

5. If we divorce the religious context from marriage, and called the new contract a civil union, we can also dismiss all religiously based moral arrangements from the contract.

6. Once the contract is pro-forma, simply a contract between two or more parties, agreeing to any legal enterprise, no outside morality is required.

7. Two or more parties can agree to any form or formation of joining for whatever period of time the parties feel fit their needs. This flows from the equal protection guarenteed in the Constitution.

For example, I can contract with Party A to build a house. He can subcontract it out to many other parties. As long as all aspects of the contract are satisfied, the contract is valid. The same principles can be applied to a civil contract, because, in fact, the civil contract is exactly that, a contract. It need not be limited in time or to the number of parties.

While not all morality arises from religion, and some religious principles are askew, God does provide for absolutes, or for the Absoulte. Contrarily, Humanistic morality has no preset limits; the limit of this form of morality, by it nature, will always run to the slippery slope. Any true adherent to the form must be willing to look down that very slope and accept what lies at the bottom or be existentially damned to falsehood.