There is much debate over the nature of marriage, of what is the religious foundation and of what marriage means in the Christian tradition. Often I read people quoting scripture on this issue. Perhaps it is time to look at that scripture as a source of legitimacy.
Fundamentalist Christians define and defend marriage by the use of scripture. While there is no one form of marriage in the world, monogamy, polygny, polyandry etc. early Christians were exhorted not to marry. In Luke, Chapter 20:34, the Apostle says that Christ stated of marriage, "The children of this world marry and are given in marriage, but those who are deemed worthy to attain That World and the resurrection of the dead neither marry nor are given in marriage." This wording differs in the different manuscripts and codices, some extant others lost, but nearly the same passage is found in Matthew 22:29. (See Paul Kahle, The Cairo Geniza, 1958; Kahle & Caldararo , State of Preservation of the Dead Sea Scrolls, Nature, 1986; Caldararo, "Storage conditions and physical treatments relating to the dating of the Dead Sea Scrolls," Radiocarbon, v. 37, n. 1, 1994:21-32 on the survival of manuscripts; for variations in texts see). The passage here quoted is from the Concordance Bible. Others vary significantly.
Considerable discussion over the wording has been of historical interest among scholars due to the fact that early Christians shunned marriage, and the Essenes who forbade marriage according to Pliny. The passage of "those who are deemed worthy to attain That World" is significant as it appears to indicate a difference between this world and that of the resurrection or heaven. It follows a debate between Christ and others who are trying to trap him into a treasonous statement over Roman hegemony. Yet in this passage he is asked to respond to a specific question of Jewish law, that of remarriage of a woman to a dead man's brothers and who she will be marriage to in heaven, one (monogamy or all, polygamy). He is put in the position of denying one tradition or another, that is, marriage of brothers of dead men or polygamy. Some have argued that his answer quoted above is consistent with Saint Paul's reasoning that Christ chose to "walk through Samaria" that is, to create a new community separate from the strictures of traditional Judaism like the less complicated Samaria.
The reason for early Christian negative attitudes on marriage is found in writings of the late Roman period where Luke is referenced that marriage distracts believers from contemplation on Christ and the world to come. It divides the community. But also Roman law gave fathers near absolute control over their wives and children and so the early Christian fathers found themselves in conflict with the authority of the paterfamilias. Later in the Dark and Middle Ages the power of the manor lord over his serfs gave them the right to sell wife and husband separately according to G.G. Coulton (see his Medieval Village, Manor and Monastery, 1925). The Church validated both marriage and sales and thus the idea of an eternal marriage rite was in contradiction to this practice. Therefore this passage was significant in arguing that marriage was neither a sacred sacrament nor an eternal institution allowing priests to dissolve marriage at the pleasure of the lord. Trial marriages were common in Europe in the Middle Ages and often a woman might marry with several children from other men. As the population of Europe fell in the period following the invasions of the Mongols and the waves of disease of the Black Death in the 14th century, the need for labor and the rising conflict of the struggle against feudalism and the Church led to the Reformation and a redefinition of marriage. The Church's control over property and inheritance became increasingly important as the legitimacy of claims to both secular thrones and to the Vatican came into question. The battle for supremacy of power, secular or religious rose in the appointment of several popes at one time by kings and the excommunication of kings by popes. Here lies the redefinition of marriage as an institution, the Church claimed it had the sacred power to recognize births and the unions that created them as well as the legal identity of heirs. Henry VIII's power as king and other ruling lords desired independent power and the wars of the Reformation settled those claims on the battlefields of the Thirty Years War. Europe became more secular and people freer to chose their mates, inherit wealth and think for themselves. Marriage was one segment to this long conflict and yet the liberty of women and their rights to chose, to inherit and to have legal standing were yet to come.
I urge people to read Lewis Ellies du Pin's A New History of Ecclesiastical Writers, published in the 17th century. It is available in translation made by W.W.B.D. in 1692. The book collates and presents the arguments over the centuries made by the Church at its various meetings (Councils) in adapting scripture to the demands of the time. We find here explanations of why some writings were accepted others rejected. An additional discussion of Gnostic writings and the long lost Gospel of Mary is found in Hans Jonas' book on the Gnostics.