I heard today, while watching parts of The David Pakman Show, that a Navy Chaplain justified his opposition to gay marriage by saying that Christ established marriage's parameters by way of Matthew 19. So, let's look at Matthew 19 a little more.
Some background on Matthew 19. Matthew 19 is a query to Jesus by the Pharisees regarding marriage. The Pharisees asked him of men could divorce their wives whenever they wanted for whatever reason. Jesus basically responds with the explanation that men and women who are married or coupled by contracts should strive to preserve their relationship as much as possible. That both partners should attempt to do everything possible to make sure that they stay together. He was highlighting the significance of the marriage contract. It was subsistence for women in this society as well as a healthy environment for child rearing. Often when divorce happened in this time, not only was the wife divorced, but the children went with her as well. This resulted in divorced women trying to survive with children to care for and often created a severe humanitarian problem. Women could not own property and had very few work prospects available to them. So the consequences of divorce were severe for women. Jesus was speaking against men who would abandon their families to follow their...uh...desires. To simply abandon your wife and children without just cause (such as sexual immorality) was offensive to Jesus because it created life-long problems for the wife and the children and believed that such motives were not based in love, justice, or fairness. In a word, it was misogynistic.
So, why does Matthew 19 not support the assertion that Christ established the definition of Marriage here?
Matthew 19 is NOT Jesus defining Marriage as Man and Woman. It is Christ repeating the scriptures from Genesis 2:24. But there is no proof here that this is an explicit establishment of a social institution. Christ is referring here to the unique relationship that marriage brings to two people. The feelings and devotion that marriage brings. Because Christ is living in an ancient society, he only knew about the concept of man and woman unions, and had no frame of reference to address to persons of the same sex engaged in exactly the same kind of environment with the same sorts of circumstances. It's likely that Christ was referring to that specific type of union as the only one he knew. Such a reference should not be inferred as excluding committed same-sex couples, as Christ doesn't even mention it anywhere in The New Testament. The argument claiming "Well, because there were no gay people back then." is also incorrect, as Ancient Rome and Greece both had very liberal views about relationships, sex, and fraternization. Rome and Greece both were open and accepting of homosexuals, as much as any society from that time could be, anyway.
The Strong's Dictionary Root (Hebrew) H802 which means "Woman" but is also interchanged with the english word WIFE in Genesis 2, is the same root used when God creates Eve and the word Woman and wife are derived from the same root.
Later, when Christ references it, in Matt 19, we see him use the word wife, but again the words are obscure and Strong's Dictionary Root (Greek) G1135 which also means Woman, but infers wife could simply mean a woman who happens to have a man, and a man who happens to have a woman. Civil marriage in this time was a contract, usually between the groom and the father of the woman being married. So, the term wife/woman being used interchangeably could simply denote the legal status or closer-than-friendship relationship. There is no inferred spiritual significance or the like. Simply that Christ was saying in Chapter 19 of Matthew that if you abandon your wife cause you want another woman, you're being a jerk to the woman and leaving her in the dust for no good reason, which is petty and cruel. Remember, women in Greece, Rome, and Jerusalem has few rights, up to and including property rights except under the most mitigating circumstances. Christ was speaking out against the men who abandon women due to either lust, or no other good reason.
If you wish to reference the above mentioned verses, the text I used was the King James Bible with Strong's Hebrew and Greek Dictionary references which provides the root's definitions in question. E-Sword is a great option if you want to look up the verse and roots in question.
H802 - ish-shaw', naw-sheem' meaning woman, but also interchanged with wife, adulteress.
G1135 - goo-nay' Probably from the root of G1096; A woman, specifically a wife - Wife, Woman.