Marriage is the divinely ordained union between one man and one woman, ordained by God. (Genesis 2:24) It has been practiced as such by just about every culture across geographical locations and time.  Marriage is intended to be a life-long commitment, and typically requently this involves a public commitment (a wedding) where vows are exchanged to each other and before God.
Dinesh D'Souza wrote:
- Marriage requires a) two people who are b) of legal age and c) not closely related to each other who are d) one male and one female. Note that this definition excludes people who want to marry children, or guys who want to marry their sisters, or Muslims who want to take four wives, or that strange guy who wants to marry his dog.
The unity between a man and a woman in marriage is a picture or analogy of the relationship that God desires to have with his creation. The first marriage occurred nearly 6,000 years ago in the Garden of Eden, in the area of the world that we now know as the Ancient Near East. The first couple was Adam and Eve.
Bill Bennett wrote:
- Based as it is on the principle of complementarity, marriage is also about a great deal more than love. That "great deal" encompasses, above all, procreation. The timeless function of marriage is childbearing and child-rearing, and the best arrangement ever developed to that end is the marital union between one man and one woman ... 
Biblical marriage advice
1 Corinthians 7:1-16:
|“||Now concerning the things about which you wrote, it is good for a man not to touch a woman. But because of immoralities, each man is to have his own wife, and each woman is to have her own husband. The husband must fulfill his duty to his wife, and likewise also the wife to her husband. The wife does not have authority over her own body, but the husband does; and likewise also the husband does not have authority over his own body, but the wife does. Stop depriving one another, except by agreement for a time, so that you may devote yourselves to prayer, and come together again so that Satan will not tempt you because of your lack of self-control. But this I say by way of concession, not of command. Yet I wish that all men were even as I myself am However, each man has his own gift from God, one in this manner, and another in that. But I say to the unmarried and to widows that it is good for them if they remain even as I. But if they do not have self-control, let them marry; for it is better to marry than to burn with passion. But to the married I give instructions, not I, but the Lord, that the wife should not leave her husband (but if she does leave, she must remain unmarried, or else be reconciled to her husband), and that the husband should not divorce his wife. But to the rest I say, not the Lord, that if any brother has a wife who is an unbeliever, and she consents to live with him, he must not divorce her. And a woman who has an unbelieving husband, and he consents to live with her, she must not send her husband away. For the unbelieving husband is sanctified through his wife, and the unbelieving wife is sanctified through her believing husband; for otherwise your children are unclean, but now they are holy. Yet if the unbelieving one leaves, let him leave; the brother or the sister is not under bondage in such cases, but God has called us to peace. For how do you know, O wife, whether you will save your husband? Or how do you know, O husband, whether you will save your wife?||”|
Modern marriage licenses
In present-day America, 'getting married' typically involves a marriage license issued by the state government or a subdivision thereof (e.g., a county). However, marriage licenses are nowhere mentioned in Scripture; in fact, they are a relatively recent innovation and originally applied only to marriages that were otherwise forbidden.
Attacks on the institution of marriage
Any society which lessened the sanctity of marriage has perished. Ancient Rome's decline and fall was due in no small part to a growing tolerance of extramarital sex, particularly homosexual acts.
Since the middle of the 20th century, activists have sought to destroy the societal pressures that dissuade people from engaging in extramarital sex. Removing the stigma from premarital sex, creating no-fault divorce laws, exalting adultery as "stimulating", and especially de-stigmatizing homosexuality all weaken the institution of marriage.
A recent Newsweek article complains that Biblical figures have not provided good historical examples of marriage, on the grounds that Abraham begot Ishmael by a maidservant and Jacob had two wives and sons with both of their servants. The article also criticizes Jesus and St. Paul for remaining single. 
- "Because there is a natural complementarity between men and women - sexual, emotional, temperamental, spiritual - marriage allows for a wholeness and a completeness that cannot be won in any other way. (Bill Bennett, The Broken Hearth, Page 197)
- Gay Rights vs. Democracy
- The Broken Hearth, Page 197)
- Information on marriage licenses from Mercy Seat Christian Church