There is one scripture more that I cannot wholly pass over, which, to me, seems a plain prohibition of polygamy, in Levit. xviii. 18. Thou shalt not take a wife to her sister, to vex her, to uncover her nakedness, besides the other in her life-time. This respects either incest or polygamy; one of which must be meant by taking a wife to her sister. Now it cannot be a prohibition of incest; because it is said, Thou shalt not do it in her life-time; which plainly intimates, that it might be done after her death. Whereas it is certainly contrary to the law of God and nature, for a person to take his wife’s sister after her decease, as well as in her life-time. Therefore the meaning is, Thou shalt not take another wife to her whom thou hast married; by which means they will become sisters. And here is another reason assigned hereof, viz. the envy, jealousy, and vexation that would attend such a practice, as the taking another wife would be a means of vexing, or making her uneasy. And therefore the sense is, as is observed in the marginal reading; Thou shalt not take one wife to another; or, Thou shalt not have more wives than one. This is a plain prohibition of this sin; but whether some holy men, in following ages, understood the meaning of this law, may be questioned; and therefore they were not sensible of the guilt they hereby contracted. Thus we have considered some of the sins forbidden in this Commandment. Every particular instance of the breach hereof, would exceed our intended brevity, on the subject we are treating of. Therefore,
We shall proceed to consider the aggravations, more especially, of the sins of fornication and adultery; which may also with just reason, be applied to all other unnatural lusts; which have been before considered as a breach of this Commandment. And,
[1.] They are opposite to sanctification, even as darkness is to light, hell to heaven; thus the apostle opposes fornication and uncleanness, to it, 1 Thes. iv. 3, 7.
[2.] These sins are inconsistent with that relation, we pretend to stand in, to Christ, as members of his body; inasmuch as we join ourselves in a confederacy with his profligate enemies, 1 Cor. vi. 15, 16. And to this we may add, that they are a dishonour to, and a defilement of our own bodies, which ought to be the temples of the Holy Ghost, and therefore should be consecrated to him.
[3.] They bring guilt and ruin on two persons at once, as well as a blot and stain on each of their families, and a wound to religion by those who make any profession of it, as it gives occasion to the enemies of the Lord to blaspheme, Prov. vi. 33. 2 Sam. xii. 14.
[4.] They bring with them many other sins; as they tend to vitiate the affections, deprave the mind, defile the conscience, and provoke God to give persons up to spiritual judgments, which will end in their running into all excess of riot.
And to this we may add, that many sad consequences will ensue on the commission of these sins; as they tend to blast and ruin their substance in the world, Job xxxi. 9, 11, 12. debase and stupify the soul, and deprive it of wisdom, Hos. iv. 11. Prov. vi. 32. chap. vii. 22. wound the conscience, and expose the person who is guilty hereof, to the utmost hazard of perishing for ever, chap. vi. 33. chap. vii. 13, 19, 26, 27. And if God is pleased to give him repentance, it will be attended with great bitterness, Eccl. vii. 26.
II. We are now to consider the occasion of these sins to be avoided by those who would not break this Commandment, and these are,
1. Intemperance, or excess in eating or drinking; the former of which is a making provision for the flesh, to fulfil the lusts thereof; the latter confounds and buries the little reason a person was master of, and makes him an easy prey to temptation. This was Lot’s case, who kept his integrity in Sodom; yet being made drunk by his daughters in Zoar, he committed the abominable sin of incest with them, Gen. xix. 31.
2. Idleness, consisting either in the neglect of business, or indulging too much sleep, which occasions many temptations. Thus David first gave way to sloth, and then was tempted to uncleanness; and it is observed, that at the time when kings go forth to battle, 2 Sam. xi. 1, 2. and he ought to have been with his army in the field, he tarried at Jerusalem, and slept in the middle of the day; for in the evening tide he arose from off his bed; And the heinous sin he was guilty of, which was the greatest blemish in his life, ensued hereupon.