What is adultery? Adultery is intimacy with another man's wife
Adultery is usually defined as marital unfaithfulness by either the wife or the husband. But is it really the Scriptural definition of it? Adultery as the Scripture defines it always have to do with a married woman. Let me explain.
Adultery is a sin
Most Churchians believe that adultery is a sin. But what is sin? And where is adultery defined as a sin? Most of them don't know but adultery is defined as a sin in the Law. And we can only really know what sin is from the Law since sin is the transgression of the Law.
I have an article that explains in details what sin is: What is sin? Sin is the transgression of the Law
Now, as we know that sin is the transgression of the Law and the Law defines adultery as sin let us double check how does the Law defines adultery.
Adultery always involves another man's wife
If a man is found lying with a woman married to a husband, then they shall both die, the man who lay with the woman and the woman. So you shall remove the evil from Israel. If there is a young lady who is a virgin pledged to be married to a husband, and a man finds her in the city, and lies with her;then you shall bring them both out to the gate of that city, and you shall stone them to death with stones; the lady, because she didn’t cry, being in the city; and the man, because he has humbled his neighbor’s wife. So you shall remove the evil from among you.
Adultery is not simply marital unfaithfulness, that would be a vague and incorrect definition. Adultery according to the Holy Scriptures is very specific (see the above quote from the Law). Adultery always involves another man's wife or a woman who is betrothed to another man. A man (whether married or not) cannot commit adultery with an unmarried or unbetrothed woman. Period. That's why polygyny is not adultery and is not a sin.
Adultery is intimacy with another man's wife or betrothed wife.
According to the Scriptures these are the only times adultery occurs:
single man + married / betrothed woman = adultery
married man + married / betrothed woman = adultery
The important factor in these equations is the married / betrothed woman, adultery as Scripture defines it always involves a married /betrothed woman.
This also means that the following is not adultery:
single man + unmarried woman = no adultery
married man + unmarried woman = no adultery
When an unmarried woman is involved in a sexual act it's not adultery and dealt with separately.
If a man finds a lady who is a virgin, who is not pledged to be married, grabs her, and lies with her, and they are found; then the man who lay with her shall give to the lady’s father fifty shekels of silver. She shall be his wife, because he has humbled her. He may not put her away all his days. A man shall not take his father’s wife, and shall not uncover his father’s skirt.
This means that a man (whether married or single) is not committing adultery by having sex with an unmarried woman. Yes, this also means that a married man can have more than one wives and it would not be a sin.
Coveting another man's possession
“You shall not commit adultery.
“You shall not steal.
“You shall not give false testimony against your neighbor.
“You shall not covet your neighbor’s wife. Neither shall you desire your neighbor’s house, his field, or his male servant, or his female servant, his ox, or his donkey, or anything that is your neighbor’s.”
From the above verse we can see a parallel between committing adultery and coveting your neighbor's wife. Coveting your neighbor's wife is placed in a list along with coveting your neighbor's house, field, servants, cattle or anything else that belongs to your neighbor.
This is because wives are the husband's possessions just as his houses, cars or cattle. Thus, adultery is a violation of another man's possession. A man takes another man's wife (his possession). So it's not only a sexual sin with a married woman, it’s coveting and stealing someone else’s possession.
Therefore adultery is coveting, stealing and intimacy with another man's wife (including betrothed wife).