Then when lust hath conceived, it bringeth forth {n) sin: and sin, when it is finished, bringeth forth death.

(n) By sin, in this place, he means actual sin.

People's New Testament

1:15 When lust hath conceived, it bringeth forth sin. The course of sin is described as that of a birth. The sinful desire is the conception; the sinful deed, the birth; moral and eternal death, the final result.

Wesley's Notes

1:15 Then desire having conceived - By our own will joining therewith. Bringeth forth actual sin - It doth not follow that the desire itself is not sin. He that begets a man is himself a man. And sin being perfected - Grown up to maturity, which it quickly does. Bringeth forth death - Sin is born big with death.

Scofield Reference Notes

Margin sin Sin.

See Scofield Note: "Rom 3:23".

Jamieson-Fausset-Brown Bible Commentary

15. The guilty union is committed by the will embracing the temptress. "Lust," the harlot, then, "brings forth sin," namely, of that kind to which the temptation inclines. Then the particular sin (so the Greek implies), "when it is completed, brings forth death," with which it was all along pregnant [Alford]. This "death" stands in striking contrast to the "crown of life" (Jas 1:12) which "patience" or endurance ends in, when it has its "perfect work" (Jas 1:4). He who will fight Satan with Satan's own weapons, must not wonder if he finds himself overmatched. Nip sin in the bud of lust.

Matthew Henry's Concise Commentary

1:12-18 It is not every man who suffers, that is blessed; but he who with patience and constancy goes through all difficulties in the way of duty. Afflictions cannot make us miserable, if it be not our own fault. The tried Christian shall be a crowned one. The crown of life is promised to all who have the love of God reigning in their hearts. Every soul that truly loves God, shall have its trials in this world fully recompensed in that world above, where love is made perfect. The commands of God, and the dealings of his providence, try men's hearts, and show the dispositions which prevail in them. But nothing sinful in the heart or conduct can be ascribed to God. He is not the author of the dross, though his fiery trial exposes it. Those who lay the blame of sin, either upon their constitution, or upon their condition in the world, or pretend they cannot keep from sinning, wrong God as if he were the author of sin. Afflictions, as sent by God, are designed to draw out our graces, but not our corruptions. The origin of evil and temptation is in our own hearts. Stop the beginnings of sin, or all the evils that follow must be wholly charged upon us. God has no pleasure in the death of men, as he has no hand in their sin; but both sin and misery are owing to themselves. As the sun is the same in nature and influences, though the earth and clouds, often coming between, make it seem to us to vary, so God is unchangeable, and our changes and shadows are not from any changes or alterations in him. What the sun is in nature, God is in grace, providence, and glory; and infinitely more. As every good gift is from God, so particularly our being born again, and all its holy, happy consequences come from him. A true Christian becomes as different a person from what he was before the renewing influences of Divine grace, as if he were formed over again. We should devote all our faculties to God's service, that we may be a kind of first-fruits of his creatures.