God's definition of marriage can be found in Genesis 2:24: "Therefore a man shall leave his father and his mother and hold fast to his wife, and they shall become one flesh." In the Bible, the Hebrew basar is often translated as "flesh," but however it is interpreted, it always refers to the physical part of humanity. What does it mean, then, that a man and woman become "one flesh" in marriage?
In marriage how do the two become one flesh?
The most obvious way is through sex. This is borne out in 1 Corinthians 6:16 when Paul says even a man with a prostitute becomes one flesh with her. The act of sex is a manifestation of "one flesh" physically and a metaphor for the other ways a married couple joins together.
Much of the physical part of life involves maintenance—feeding, housing, repairing. A man and woman become one flesh in marriage when they share these things as a unit. A man is called to leave his parents—to step out of their home and provision—and become one flesh with his wife. As husband and wife work together in the stuff of life, they become united, and may even start to look like each other.
The flesh is also how we actively respond to what Jesus has done for us. God has prepared good works ahead of time for us to accomplish (Ephesians 2:10). As "one flesh," a married couple coordinates their efforts to ensure they get the work done—both as individuals and as a team. As any couple surrounded by kids, church, work, and friends knows, husbands and wives cannot fulfill their God-given duties unless they work together.
Beyond practical and spiritual matters, we need to realize that our flesh belongs to our spouse (1 Corinthians 7:4), and the way we treat our body needs to reflect the respect we have for our spouse. As trivial as it may sound, things like fitness, hair styles, and tattoos should always be considered with your spouse in mind. Falling into poor health through negligence directly affects the lifestyle of your spouse. Asking for input regarding clothes and hair shows that you care how your spouse sees you. This also applies to physical behavior. It is disrespectful to flirt, dress revealingly, or in any other way use your body and actions to infer that you are not one flesh with your spouse.
The world is going to try to pull all of this apart. It's going to say that your body is your own, to use and treat as you see fit. It's going to insist you have to look a certain way or do certain things with your body in order to fit in. It will also lure you away from the united home life in the name of freedom, independence, and what you "deserve." Instead, God says that, in marriage, a couple becomes one flesh, to live together, honor each other with their bodies, and serve Him with their combined lives.
Biblically, what constitutes a marriage?
What does the Bible teach about marriage?
Is sex intended only for procreation or can married couples have sex just for pleasure?
What grounds for divorce does the Bible provide?
What are biblical steps to restore a marriage?
Truth about Marriage