Living Christianity: The Ten Commandments (Marriage and Sex, Part 1)

November 19, 2019

by Peter Amsterdam

(Points for this article are taken from Christian Ethics, by Wayne Grudem.1)

The next topic in this series on Christian ethics is the seventh commandment, “You shall not commit adultery.”2 The definition of adultery according to the American Heritage Dictionary is Consensual sexual intercourse between a married person and a person other than the spouse. Throughout both the Old and New Testaments, this commandment is repeated numerous times.3 The Hebrew word used in the Old Testament for adultery is na’aph, and in the New Testament Greek the word moicheuo has the same definition.

This commandment can be viewed in a sense as a directory which contains a number of subtopics. In addition to adultery, it encompasses topics such as the institution of marriage, as well as divorce and remarriage; being single, having children, birth control, infertility, and adoption; and sexual matters including sex before marriage, fornication, incest, pornography, and homosexuality. Through several articles on the themes of marriage and sex, Living Christianity will look at each of these subtopics.

Sexual ethics in the Western world underwent monumental change in the latter part of the 20th century, resulting in a major shift away from biblical teaching on the subject, and in many things that are prohibited in Scripture becoming widely accepted in contemporary society. In addressing these topics, the focus will be on what the Bible teaches. However, not all Christians or denominations agree on how to interpret the teachings regarding marriage and sexuality in Scripture, so where there is major disagreement among Christian denominations, I will try to present the different views.

The purpose of the seventh commandment is to protect marriage, and the understanding of marriage within Scripture is a lifelong relationship between a man and woman. While same-sex marriages are recognized in a number of nations, the focus here will be on the biblical view of marriage.

The first chapter of Genesis states:

God created man in his own image, in the image of God he created him; male and female he created them. And God blessed them. And God said to them, “Be fruitful and multiply.”4 

As Genesis continues, we find that Adam, the man God had created, was alone. In chapter two, we read that God created Eve, the first woman, from Adam’s side. After doing so, God said:

Therefore a man shall leave his father and his mother and hold fast to his wife, and they shall become one flesh.5 

In these verses we see marriage, the first human institution, established. It is the only institution which predates the fall of humans into sin, which occurs in Genesis chapter three.

The biblical understanding of marriage is a lifelong covenant partnership. A covenant is a solemn agreement made between two parties; in the case of marriage, between a husband and wife.

The LORD was witness between you and the wife of your youth, to whom you have been faithless, though she is your companion and your wife by covenant.6

In the marriage covenant, a man and woman promise each other that they will be faithful to their marriage as long as they live.

Christian wedding ceremonies refer to God’s presence as a witness to the couple’s wedding vows. Christian ceremonies usually state something along the lines of We have come together here in the sight of God and in the presence of this congregation to join together this man and this woman in holy matrimony.

According to Scripture, all marriages, whether Christian or not, are covenants made before God. When Jesus was speaking about marriage, He referred to what was written in the book of Genesis, that the husband and wife shall become one flesh. So they are no longer two but one flesh. He then added, What therefore God has joined together, let not man separate.7 The point Jesus made was that when a couple gets married, there is a fundamental change, as God Himself has united the couple together in a spiritual union, and they are “one flesh.” This makes every marriage ceremony a sacred occasion, which God is a witness to, whether the couple believes in God or not.

Every marriage is the beginning of a new family, distinct from the families of the bride and groom. Genesis speaks of the husband leaving his father and mother [to] be united to his wife.8 As such, a new household is established. Marriage, in many societies, also changes the couple’s legal status. If one spouse dies, the remaining spouse has inheritance rights. If one spouse becomes ill, the other has authority and responsibility to care for the one who is sick and to make decisions regarding their medical care. If they have children, they have authority and responsibility for raising them.

The decision to marry is one of the most important decisions a person makes in their life. Scripture weighs in on who a believer should marry. In the Old Testament, we read that God forbade the Jewish people to marry people who worshipped other gods.

“When the LORD your God brings you into the land that you are entering to take possession of it, and clears away many nations before you ... You shall not intermarry with them, giving your daughters to their sons or taking their daughters for your sons, for they would turn away your sons from following me, to serve other gods.”9 

We find the classic example of this in the life of King Solomon, who married numerous foreign wives.

When Solomon was old his wives turned away his heart after other gods, and his heart was not wholly true to the LORD his God, as was the heart of David his father.10 

There are, however, examples in Scripture of non-Jews who converted to Judaism and married Israelites, such as Ruth.11

In the New Testament, we find the statement:

Do not be unequally yoked with unbelievers. For what partnership has righteousness with lawlessness? Or what fellowship has light with darkness?12

While this wasn’t specifically addressing marriage, the principle it teaches can be understood to apply to the choice of a spouse. Elsewhere, the apostle Paul wrote:

A wife is bound to her husband as long as he lives. But if her husband dies, she is free to be married to whom she wishes, only in the Lord.13

In writing the “only in the Lord” clause, the apostle Paul meant that while the widow could remarry, she should only marry another Christian believer. While Paul only addressed widows in the passage, it is generally understood within Christianity that this indicates that Christians should marry other believers. Of course, many Christians have married non-Christians and have had wonderful marriages, sometimes resulting in the non-Christian spouse becoming a Christian.

While these New Testament statements don’t specifically forbid marriage between believers and non-believers, they offer wise counsel regarding who one chooses to marry. Generally speaking, a Christian spouse may not be in a position to fully live their faith if they marry a non-believer; as in order to be in sync with their non-Christian spouse, they may need to move the Lord and their faith more to the margins of their life. It may put some restrictions on practically living and practicing their faith. For example, it might hinder their devotional life, raising their children in the faith, showing hospitality to other believers, tithing, supporting missionaries, or having fellowship with other believers, in order to preserve peace in the home.

Conversely, if the believer in the marriage is actively involved in the practice of their faith, the non-believing partner might be marginalized. If the non-Christian husband or wife doesn’t understand the point of studying the Bible, prayer, witnessing, or gathering with other Christians either in church or in small groups, then they won’t participate in these activities along with their believing spouse. In such a case, the oneness of the marriage, the deep unity between the spouses, may not flourish as it should, as one partner will be left out of the other person’s important commitments. In such instances, there can be a lot of stress in the marriage, which can lead to the marriage dissolving; or, the marriage may stay intact because of one spouse or the other capitulating in some aspects, but this may leave both parties feeling lonely and unhappy.

Of course, all married couples have some disagreements, arguments, and challenges to overcome. However, Christian couples have the common denominators of their faith, Scripture, prayer, and the Holy Spirit, which yoke them together and can help them overcome their differences or give them the grace to lovingly accept them. The primary difference between a Christian marriage and a non-Christian marriage is that Jesus is present and is hopefully at the center of the marriage. When a couple is united in Christ, their goal is to grow in Christlikeness through their marriage, and when they do, a strong Christian marriage is formed.

Christianity calls for marriage partners to practice mutual submission as husband and wife and serve each other in love. We are to love our spouse unconditionally, as Christ loves us, as well as respect them for who they are. Our marriage is our most important earthly relationship, and while other relationships are important, none should be put before this one. Though after some time spouses may not feel as “in love” as they did when they first married, strong marriages last because they have made a commitment to each other in the presence of God, which goes beyond their present emotional feelings.

In the book of Genesis we read that God said, “It is not good that the man should be alone; I will make him a helper fit for him,” and thus He made a woman from a rib He took from Adam. As such, God made two of one. When a couple is married, He makes one of two. Marriage unites a man and a woman so that they become one flesh.14


Unless otherwise indicated, all scriptures are from the Holy Bible, English Standard Version, copyright © 2001 by Crossway Bibles, a division of Good News Publishers. Used by permission. All rights reserved.

1 Wayne Grudem, Christian Ethics (Wheaton: Crossway, 2018).

2 Exodus 20:14.

3 Deuteronomy 5:18; Matthew 5:27, 28; Matthew 19:18; Mark 10:19; Luke 18:20; Romans 13:9; James 2:11.

4 Genesis 1:27–28.

5 Genesis 2:24.

6 Malachi 2:14.

7 Matthew 19:6.

8 Genesis 2:24 NIV.

9 Deuteronomy 7:1–4.

10 1 Kings 11:4.

11 Ruth 1:16.

12 2 Corinthians 6:14.

13 1 Corinthians 7:39.

14 Genesis 2:24.