This commandment for Israel concerned any kind of sexual immorality: fornication—sex between unmarried men and women; adultery—sex between a married person or persons and someone who is not their spouse; incest—sex between immediate family members; rape—the forced sexual assault of an individual; sodomy, homosexuality, lesbianism—sex between members of the same sex; bestiality—sex between a man or woman and an animal; whoredom—sex that is solicited for money or other favors; uncleanness—unclean acts of sex, even between a married couple. It also included acts of immorality that did not include intercourse—nakedness between non-married people or lewd behavior. God also forbad the marriage between the children of Israel and the heathen people around them. Although God created man with sexual desires and as the means for propagating the human race, He also placed boundaries that forbid casual sex, recreational sex, or any sexual acts not within marriage. Because sex outside of Biblical marriage can be such a devastating sin to a person and society, God made this a sin punishable by death. There were, however, other judgments besides stoning for those sexual offenses that were less damning—such as a single man and woman involved in fornication would be forced to marry one another. All of the various sexual laws of the Old Testament for Israel were God’s means for preserving their society and to keep it from self-destruction.

Exo 20:14 Thou shalt not commit adultery.

Lev 20:10 And the man that committeth adultery with another man's wife, even he that committeth adultery with his neighbour's wife, the adulterer and the adulteress shall surely be put to death.
11 And the man that lieth with his father's wife hath uncovered his father's nakedness: both of them shall surely be put to death; their blood shall be upon them.
12 And if a man lie with his daughter in law, both of them shall surely be put to death: they have wrought confusion; their blood shall be upon them.
13 If a man also lie with mankind, as he lieth with a woman, both of them have committed an abomination: they shall surely be put to death; their blood shall be upon them.
14 And if a man take a wife and her mother, it is wickedness: they shall be burnt with fire, both he and they; that there be no wickedness among you.
15 And if a man lie with a beast, he shall surely be put to death: and ye shall slay the beast.
16 And if a woman approach unto any beast, and lie down thereto, thou shalt kill the woman, and the beast: they shall surely be put to death; their blood shall be upon them.
17 And if a man shall take his sister, his father's daughter, or his mother's daughter, and see her nakedness, and she see his nakedness; it is a wicked thing; and they shall be cut off in the sight of their people: he hath uncovered his sister's nakedness; he shall bear his iniquity.
18 And if a man shall lie with a woman having her sickness, and shall uncover her nakedness; he hath discovered her fountain, and she hath uncovered the fountain of her blood: and both of them shall be cut off from among their people.

Lev 19:29 Do not prostitute thy daughter, to cause her to be a whore; lest the land fall to whoredom, and the land become full of wickedness.

Deu 7:1 When the LORD thy God shall bring thee into the land whither thou goest to possess it, and hath cast out many nations before thee, the Hittites, and the Girgashites, and the Amorites, and the Canaanites, and the Perizzites, and the Hivites, and the Jebusites, seven nations greater and mightier than thou;
2 And when the LORD thy God shall deliver them before thee; thou shalt smite them, and utterly destroy them; thou shalt make no covenant with them, nor shew mercy unto them:
3 Neither shalt thou make marriages with them; thy daughter thou shalt not give unto his son, nor his daughter shalt thou take unto thy son.
4 For they will turn away thy son from following me, that they may serve other gods: so will the anger of the LORD be kindled against you, and destroy thee suddenly.

Exo 22:16 And if a man entice a maid that is not betrothed, and lie with her, he shall surely endow her to be his wife.
17 If her father utterly refuse to give her unto him, he shall pay money according to the dowry of virgins.

In the New Testament we also see a further broadening of the moral principles behind this law. Jesus taught that adultery could be committed in the heart of a man or woman even without any outward sexual act. Society, led by the lustful desires of man’s wicked heart, has opened the flood gates for this kind of sin. Pornography of every kind has invaded the world through books, magazines, videos, computers, and television. So-called soft-porn has been made acceptable to many in the offerings of romance novels, television shows, music videos, video games, mainstream magazines, and advertising. We have become inundated by the bombardment of impure sexual images and thoughts. Sexual enticements are feed to our children in school, on prime-time television, and in the movies. The sin of adultery is now scoffed at, and fornication is even promoted as being healthy. Those who promote abstinence are ridiculed, and those who promote free-sex and infidelity are the heroes of our youth. Even religious and governmental leaders at all levels have promoted this lifestyle by their examples and legislation. Man’s abandonment of the moral teachings from the Bible is beginning to take a devastating toll upon the human race. Mankind has sown the wind, and we are starting to reap the whirlwind. Divorce, broken homes, illegitimate children, and sexual diseases have been exacting a horrible price upon modern society.

Matt 5:27 Ye have heard that it was said by them of old time, Thou shalt not commit adultery:
28 But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart.

Hos 8:7 For they have sown the wind, and they shall reap the whirlwind: it hath no stalk: the bud shall yield no meal: if so be it yield, the strangers shall swallow it up.

Christian liberty, of course, does not excuse a child of God from this kind of sin. God’s children are reminded that “Marriage is honourable in all, and the bed undefiled: but whoremongers and adulterers God will judge.” Even our sanction to serve God hinges upon our sexual purity. The Apostle Paul, in dealing with the Corinthian church, had to rebuke their attitude for this kind of liberality. This church had so promoted the freedom of Christ that they allowed every kind of sin to invade their assembly. Their witness to the outside world was making a mockery of Christ and what He came to do—“save His people from their sins.”

Heb 13:4 Marriage is honourable in all, and the bed undefiled: but whoremongers and adulterers God will judge.

1 Cor 6:18 Flee fornication. Every sin that a man doeth is without the body; but he that commiteth fornication sinneth against his own body.
19 What? know ye not that your body is the temple of the Holy Ghost which is in you, which ye have of God, and ye are not your own?
20 For ye are bought with a price: therefore glorify God in your body, and in your spirit, which are God's.

1 Thes 4:3 For this is the will of God, even your sanctification, that ye should abstain from fornication:
4 That every one of you should know how to possess his vessel in sanctification and honour;
5 Not in the lust of concupiscence, even as the Gentiles which know not God:

1 Cor 5:1 It is reported commonly that there is fornication among you, and such fornication as is not so much as named among the Gentiles, that one should have his father's wife.
2 And ye are puffed up, and have not rather mourned, that he that hath done this deed might be taken away from among you.
3 For I verily, as absent in body, but present in spirit, have judged already, as though I were present, concerning him that hath so done this deed,
4 In the name of our Lord Jesus Christ, when ye are gathered together, and my spirit, with the power of our Lord Jesus Christ,
5 To deliver such an one unto Satan for the destruction of the flesh, that the spirit may be saved in the day of the Lord Jesus.

Matt 1:21 And she shall bring forth a son, and thou shalt call his name JESUS: for he shall save his people from their sins.

As with all the commandments, there is also a deeper meaning to those in Christ. In a natural sense, what does the act of adultery do to the one we sin against—our spouse? In going outside of marriage to find sexual gratification we are telling our marriage partner that our union with them is secondary to our desires; we are implying that we are not satisfied with the love we receive from them; and we are denying them the rightful benefit of having their desires met. We also bring into the marriage bed uncleanness, disease, and the possibility of having children other than our spouse’s. As Christians we commit the same kind of offences against our Lord. We are the bride of Christ. We have become one with Christ by the indwelling Holy Spirit. He deserves the same kind of fidelity to Him that we show to our natural mates. Christians like to say that God is first in their lives; and that gives them an avenue to do other things which they find pleasure in. What if we said to our spouse ‘You are number one in my life, but I also desire to mate with other sexual partners.’  Or  ‘You are first in my life, but I also have my work, the bowling league on Monday, the golf league on Tuesday, the softball team on Wednesday, gym night on Thursday, Friday night cards with my friends, my hunting and fishing on the weekends, and other activities that don’t really involve you.’ Would that be acceptable to the one we have committed ourselves to love and to cherish?—no, and neither is it to Christ. We commit spiritual adultery when we give our affections, time, and talents to the world or any other god or idol besides Christ. Everything we do should be with His honor and glory in mind. Our families, our jobs, our recreation, how we spend our time and money or use our talents, should all be an expression of our love and devotion to Him. He knows we have obligations to our families, and we also have needs and proper desires. Our love for Him is what makes all other relationships and occupations of our time meaningful and fulfilling. Those who begin to fall out of love for Christ and instead give their affections to the world are breaking this commandment of grace. Furthermore, like a jealous husband, Christ will chasten His bride to return to Him.

2 Cor 11:2 For I am jealous over you with godly jealousy: for I have espoused you to one husband, that I may present you as a chaste virgin to Christ.

Rom 7:4 Wherefore, my brethren, ye also are become dead to the law by the body of Christ; that ye should be married to another, even to him who is raised from the dead, that we should bring forth fruit unto God.

1 Cor 6:15 Know ye not that your bodies are the members of Christ? shall I then take the members of Christ, and make them the members of an harlot? God forbid.
16 What? know ye not that he which is joined to an harlot is one body? for two, saith he, shall be one flesh.
17 But he that is joined unto the Lord is one spirit.

Jam 4:4 Ye adulterers and adulteresses, know ye not that the friendship of the world is enmity with God? whosoever therefore will be a friend of the world is the enemy of God.

1 John 2:15 Love not the world, neither the things that are in the world. If any man love the world, the love of the Father is not in him.
16 For all that is in the world, the lust of the flesh, and the lust of the eyes, and the pride of life, is not of the Father, but is of the world.

Rev 2:1 Unto the angel of the church of Ephesus write; These things saith he that holdeth the seven stars in his right hand, who walketh in the midst of the seven golden candlesticks;
2 I know thy works, and thy labour, and thy patience, and how thou canst not bear them which are evil: and thou hast tried them which say they are apostles, and are not, and hast found them liars:
3 And hast borne, and hast patience, and for my name's sake hast laboured, and hast not fainted.
4 Nevertheless I have somewhat against thee, because thou hast left thy first love.

Rev 3:14 And unto the angel of the church of the Laodiceans write; These things saith the Amen, the faithful and true witness, the beginning of the creation of God;
15 I know thy works, that thou art neither cold nor hot: I would thou wert cold or hot.
16 So then because thou art lukewarm, and neither cold nor hot, I will spue thee out of my mouth.
17 Because thou sayest, I am rich, and increased with goods, and have need of nothing; and knowest not that thou art wretched, and miserable, and poor, and blind, and naked:
18 I counsel thee to buy of me gold tried in the fire, that thou mayest be rich; and white raiment, that thou mayest be clothed, and that the shame of thy nakedness do not appear; and anoint thine eyes with eyesalve, that thou mayest see.
19 As many as I love, I rebuke and chasten: be zealous therefore, and repent.