A) If polygamy is not lust,
what is?
Lust is commonly misunderstood and the usage of the word is usually abused. Lust
does not equal sex. Lust is not having sex. Lust is not even having more sex. Lust is
coveting what you are not supposed to possess - including the excesses, taking what
belongs to others, indulging in what is not yours. It is not how much or how little that
one is involved with for it depends on the grace and capacity of each individual, which
differs one from another. Lust is wallowing in that which is not yours or in excesses that
are beyond your ability and grace to handle, and it may just be about anything, including
power, money, sex, territory, and even ministry, knowledge and seemingly casual
relationships, love and authority over anothers life. So it is required of a man to
know himself, to know what is his and what is not and to know the will of God and his
position in all matters of his life and relationships around him. And these he will not
know until he knows his God.
Thus, whether you are a man or a woman, even secretly desiring for or fantasizing
(whether sexually or not) after another woman or man, that by the scriptures you know you
are not supposed to possess, is already an unfaithful act of adultery in the heart. This
may even be in any form of representations such as things, pictures or words. That's why
indulging in pornography, celebrity worship and even admiration of unrighteous
personalities in any form are lustful. And having such desires over things that one is not
supposed to possess is covetousness and theft in the heart. On the other hand, possessing
things in your heart that you are supposed to have but not yet have, is faith. Love does
not covet (envy - 1Cor 13:4), but love enlarges in the promises of God for oneself.
The experience of David is a classic example to define what is lust and what is not.
The David's sin of adultery was not that of possessing more wives (1Sam 5:12,13) but that
of taking another man's wife. 2 Sam 12:8-9, 'I gave you
your master's house and your master's wives into your keeping, and gave you the house of
Israel and Judah. And if that had been too little, I also would have given you much more!
'Why have you despised the commandment of the LORD, to do evil in His sight? You have
killed Uriah the Hittite with the sword; you have taken his wife to be your wife, and have
killed him with the sword of the people of Ammon. (NKJ)
B) What then is being unfaithful to your wife?
To be unfaithful is to default in a covenant and in this case, a marriage covenant.
And normally such a question refers to having an intimate or sexual relationship with
another woman. So I shall answer this question in this context. Under the law of the
Romans which is strictly monogamous, having another wife would be breaking the covenant,
rendering a man unfaithful, but in Gods law, polygamy (polygyny) is permissible when
it is practised according to the written and oral law as in the case of the Biblical
patriarchs and founding Christians. So this becomes a question of which law one is living
under that he is considered faithful or unfaithful. If one is living by the Word and is
governed by its principles, then being responsibly polygamous to all his wives is not
being unfaithful in any way. In Christ, we are free from the law and rudiment of the
world.
However in a broader context, as long as a man is irresponsible (whether monogamous or
polygamous) in protecting or caring for his wife as committed or if the wife is
insubmissive as committed in the marriage covenant, then in the strictest sense,
unfaithfulness is already committed.