“Then, when desire has conceived, it gives birth to sin; and sin, when it is full-grown, brings forth death”
and sin, when it is full-grown,
Sin produces something as well – death. “Full-grown” has the idea of bring to completion, finish, come to completion, be fully formed. The idea is that when sin has fully run its course, it will bring forth death. Sin develops like an embryo in a womb and has a way of coming to life.
brings forth death
As lust gives birth to sin so sin gives birth to death. It is ironic that birth brings death! If we allow ourselves to go through the full cycle of lust and sinning then our fellowship with the Lord will die. If we stay in a state of alienation to God in our time on earth (not in eternity) then God may kill us physically.
“For this reason many are weak and sick among you, and many sleep [died]. For if we would judge ourselves, we would not be judged. But when we are judged, we are chastened by the Lord, that we may not be condemned with the world” (1 Corinthians 11:30-32).
“If anyone sees his brother sinning a sin which does not lead to death, he will ask, and He will give him life for those who commit sin not leading to death. There is sin leading to death. I do not say that he should pray about that” (1 John 5:16).
This “death” stands in striking contrast to the “crown of life” of verse 12. If we let sin dominate us, our spiritual life will be like a stillborn baby. Death is separation. Sin always separates us from God.
The hope of sin results in stillborn satisfaction.
Our will is influenced by our desire. Sin is more than a single action; it is the result of a process. The sequence of lust, deception, choice and disobedience will produce spiritual death. The earlier we address ourselves in this process, the easier it will be to overcome sin. Conversely, the longer we wait in the process the more difficulty we will have in overcoming the sin.
Before we became Christians, we were enslaved to lust (Ephesians 2:1-3; 4:17-19; 1 Thessalonians 4:5). Lust is morally neutral. It is an illegitimate desire. The hope of sin results in stillborn satisfaction.