“They Shall Be One Flesh”

Introducing the Seventh Commandment

4 min

Marriage is God’s first human institution. Before He instituted the state or the church, God first made the family. When the Creator took the rib of Adam and fashioned Eve as a “help meet” for Adam, He said, “Therefore shall a man leave his father and his mother, and shall cleave unto his wife: and they shall be one flesh” (Genesis 2:24). It would be wise for us to recognize God’s purposes and His right to determine how marriage should function.

Because God ordained marriage as the foundation of human society, Satan has long been engaged in the process of undermining and destroying marriage and the family. In our own generation, the Biblical family is under attack like never before in human history. Manhood and womanhood are being redefined. Promiscuity and fornication no longer carry a stigma of shame. Tragically, many children are commonly born out of wedlock, and they grow up without the stable influence of father and mother. Divorce is common, even within the church. Our courts and judges make divorce easy, and civil penalties against adultery have long been removed from our penal codes. Our schools systematically teach children that perversions are normal. Sins that God calls abomination have now become socially acceptable. Good is called evil, and evil is called good.

Against this avalanche of change, the seventh commandment still affirms through the ages of time: “Thou shalt not commit adultery.” This commandment stands as a bulwark for a God-honoring society, defending the vitally important institution of marriage.

As Christian men, we must maintain the truth of God in the face of the lies of Satan. We can apply the seventh commandment in a personal and practical way:

I am to flee the lusts of the flesh and guard my heart, knowing that God designed marriage as a covenant of love between a man and a woman for life (Matthew 5:27–28).

This month, we are going to survey marriage and family from their foundations in the Book of Genesis to the practical commands given by the Apostle Paul in his epistles to the churches. Seeking to gain and maintain a pure heart, we will examine the words of the Lord Jesus and how He viewed marriage and adultery. We will also look at the lives of men in Scripture and in history who resolutely guarded their hearts and lived as pure, Godly men in the midst of an impure, ungodly world.

We begin by examining the roots of marriage in the Book of Genesis and why the seventh commandment given at Mount Sinai is so foundational.

God said of Adam that “It is not good that the man should be alone” (Genesis 2:18). This statement was made in the Garden of Eden, where all was “very good.” Adam was incomplete without Eve; he was unable to do the work God had created him to do without her assistance and companionship. Therefore, the LORD said, “I will make an help meet for him.”

The elegant Hebrew expression “an help meet for him” means that Eve was specifically created as a suitable and complementary helper to Adam. She was his counterpart—his helper, his friend, his companion—and she was made by God to be exactly suitable for him. Together, they were to fulfill the Lord’s mandate to “be fruitful, and multiply, and replenish the earth, and subdue it: and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth” (Genesis 1:28).

When Eve was presented to Adam, he exclaimed, “This is now bone of my bones, and flesh of my flesh” (Genesis 2:23). These are the first recorded words of human speech. They are poetical in form and a grateful recognition of the gift of God.

God Himself instituted marriage by saying that a husband and his wife were to become “one flesh.” They are no longer two but one. They stand in a covenant relationship with each other and with God Who ordained their union. From the very beginning, Satan began to attack Biblical marriage. When he singled out Eve and sought to separate her from Adam by temptation, Satan’s goal was to undermine God’s created order.

Interestingly, adultery was recognized as sin even before Mount Sinai. In Genesis Chapter 12, Abraham lied about his relationship with Sarah and told Pharaoh that she was his sister. Later, when the Pharaoh of Egypt discovered the deception, he was horrified by the thought that he might have taken a man’s wife as his own (Genesis 12:18–19). Likewise, Abimelech, king of Gerar, returned Sarah to Abraham when God told him in a dream that “she is a man’s wife” (Genesis 20:3).

Another aspect of breaking the seventh commandment—“Thou shalt not commit adultery”—is polygamy. Very early in the Genesis record, we find the first case of polygamy in Genesis 4:19. Later, in another case, Abraham took Hagar as his concubine. The action brought strife, bitterness, and heartbreak upon his family (Genesis 16:4). When Jacob took two wives and two concubines, we see a long and devastating pattern of jealousy, heartbreak, and immorality in the next generation. By contrast, the purity of Isaac’s marriage to Rebekah and Joseph’s faithfulness in the face of temptation are regarded as noble examples of purity and virtue.

When God said on Mount Sinai, “Thou shalt not commit adultery,” He was literally setting in stone that which He had already revealed to man from the beginning. In the Law of God given to Moses, adultery was punished by capital punishment, demonstrating the importance of the marriage relationship. To commit adultery is to defy the Creator, violate a sacred covenant, and corrupt that which is holy.

Next week, we will consider the seventh commandment in the light of the prophets and see the link between adultery and idolatry that is made in the Old Testament. In the biographical sketch, we will see a shining example of purity in the life of Joseph, the Hebrew slave in the land of Egypt who faithfully refused to commit adultery with his master’s wife. May God give us all, as Christian men, the courage and moral fortitude to uphold the sanctity of marriage as a “one-flesh” covenant established by God for our good and His glory.

This article is from our Matters of Life & Death teaching series.

Get these articles delivered to your inbox every week.

"*" indicates required fields

We’ll send you emails twice a week, on Tuesdays & Thursdays, with articles from our Matters of Life & Death teaching series. Occasionally, there may be a few updates on other events or resources that may be relevant to you.

From Our library

Recent Posts

Basic Life Principles

Timeless truths for our lives and relationships

Five Life Roles

Understanding basic roles we fulfill in our relationships throughout life


Thought-provoking articles on practical topics

Character Qualities

Being conformed to the likeness of Christ

Matters of Life & Death

A teaching series for men drawn from the Ten Commandments

Life Questions

Biblical answers to life's biggest questions

Commands of Christ

Pursuing the heart of the Great Commission


Weekly discussions on the Commands of Christ


Engaging presentations on important life lessons

Family Events

Fun & fellowship around the Word of God

Discipleship Opportunities

Cultivate personal & spiritual growth

Character Curriculum

Biblical Character Illustrated Curriculum for children

Embassy Media

On-demand media library

Study Materials

Resources for individual or small group study

All Events

Calendar of upcoming events

About IBLP

Christ-centered discipleship for individuals and families

News & Reports

Updates from ministry around the globe

Alumni: Share Your Story

We’d love to hear from you!