Dingeroo, I'll leave your comments open for debate, as it pertains to the topic. I would like to pose a few corrections:
Recorded History dates back to 3200 B.C., in Mesopotamia. Mesopotamia's marriage laws were essentially property laws. The civil contract of owning a slave differed only slightly from that of owning a wife. In fact, the Mesopotamian equivalence to the word, Husband, translated to "owner of wife." So the answer is no, it was not a religious sacrament. ~
http://ehistory.osu.edu/world/articles/ArticleView.cfm?AID=58
As previously stated, the confusion begins with a failure to identify the history and functionings of judeo-christian theocracies. For example, when other religions arose from the conflicts within Judaism, in that the Israelite tribes were previously governed by Judges, and when they merged to create the Kingdom of Israel, they codified and collated their laws
(these were initially not laws of God, but of man). Judaism consists of many books, each addressing governance, agriculture, health, civil law, criminal, and religion. When religions "broke" from Judaism, such as the Christianity and later Muslim religions, they took with them "parts" of various books from Judaism. There are still divergences from Judaism, some of which eschewing ancient rules that existed to protect health, such as eating pork. Those particular rules no longer apply in countries where trichinosis is under control. Indeed, many ancient rules, handed down over the ages, no longer apply because of the knowledge and advances we have gained over time. But still, there are some who adhere to those rules because they have been brought up with the belief that the laws of ancient man and the beliefs in God are one and the same.
Returning to the argument that marriage is a sacrament, some Jewish denominations recognize same-sex marriage and emphasize it is about the bond between two people, irregardless of physical accouterments. Same for some Christian denominations. Indeed, what would be the answer for a hardliner on such issues as a woman or man not being able to procreate, or that of a hermaphrodite, someone born with both male & female organs? Or of those who are androgynous, or display one more more characteristics of each gender? While it is easy to claim male & female, it is disingenuous to the reality of nature and the millions of cases in which gender is not so firmly defined.
In many other places in the world, marriage was a civil contract, not a religious one, and many places still do not associate marriage with religion. Covering a few other religions and beliefs, we can touch upon Confucianism which, although more a philosophy than a religion, nonetheless governs peoples actions as would a religion and takes upon the role of unifying clans (families). For the purpose of growing the clan, couples who are not able to have children are not desired (this would include those who cannot procreate due to infertility). But, this does not preclude marriage, only makes it not helpful as a utility for uniting clans.
Then there is Taoism, which identifies our Western flaw of divorcing spirituality from sexuality. In this respect, the goal is to embrace sex and sexuality as something that brings us happiness and that being with the person you wish to be with serves to fulfill. Rules imposed to restrict two (or more) people from being together is anathema to Taoism.
And let's return to Christianity, wherein Archbishop Desmond Tutu, a retired Anglican bishop and rights activist, argued that nobody is the stepchild of God and that persecuting and/or excluding any of God's children is blasphemy. This goes hand in hand with not judging others, as stated in the Bible under many verses.