This article is intended to give a historical perspective on the concept of "marriage". Hopefully it helps to assist in the current debate over "same-sex" unions.
Marriage as a concept predates governments. In some cases, it was an attempt by a man to be sure of his part in the procreation process. He paid a "bride price" for exclusive sexual rights of the bride. Thereby he confirmed paternity of the offspring as much as possible. In ancient times there was no specific ritual (ceremony) required. A simple agreement between the parties was sufficient ("common law").
The Romans had two distinctly different kinds of marriage. One the women lost all inheritance from her former family while gaining same in the new one. The other, the woman retained her inheritance while not getting any from the new one.
Until 325, marriages between "Christians" was considered a private matter. No uniform ceremony or religious rite was required for the union to be recognized.
Women were not "required" to take her husbands last name until the 12th Century. It was not until well into the 16th Century that parental permission was required.
Christian marriages in Europe were by mutual consent until 1545. Declaration of intention to marry and upon the subsequent physical union of the parties. The couple would promise verbally to each other. The presence of a priest or witnesses was not required. "I marry you" meant you were married. "I will marry you" was the "engagement". The main function of Christian Churches was to register the marriages. This was repeated in the "family Bibles". In 1563, The Council of Trent declared that a "Roman Catholic" marriage had to be done by a priest in the presence of two witnesses.
It was not until John Calvin that the "dual" concept of state registration and church ceremony was presented in the Marriage Ordinance of Geneva. The Marriage Act of 1753, full title "An Act for the Better Preventing of Clandestine Marriage" was enacted to 'defend marriage'. Anglican clergy had been marrying people without "banns" or notice being given which was against the "canons" of the Church.
The governments were happy for these events. It meant more income for "licenses". The concept of "Civil Unions" was formalized in 1989 in Denmark. In actuality, it has been what the licenses were for all along. Once judges and others not clergy performed the ceremonies these were not "religious" rites.
One great myth about marriage is that the person performing the ceremony has to be ordained. If this were so, Jewish weddings in any Synagogue would not be valid because rabbis are not ordained. No Muslim ceremony would be legal because, again, clergy is not ordained. The requirement many places is simply that "a ceremony be performed". In California, there are two forms of license. One is "confidential". This requires no witnesses but is only good for a ceremony performed in the county of issuance. The other can be used anywhere in California. Proof of the location of the ceremony is not required.
There has always been a separation between the "civil" part of marriage and the "religious" part. Why not just recognize this formally? The "religionists" can have theirs and the gays get the same "civil" rights as everyone else.