The Idea in Brief
The “sin leading to death” is any sin committed against any congregation of believers who comprise the Body of Christ. In these cases, believers are not to forgive (loosen on earth = loosen in heaven) but instead to hold believers accountable (bind on earth = bind in heaven). Some examples of such sins include, but are not limited to, deception relating to financial matters; deliberate false teaching; and/or open sexual immorality. These sins lead to death, which means deliverance over to Satan (Hymanaeus and Alexander in Asia Minor); deprivation of physical health (“Jezebel” in Thyatira); and/or immediate physical death (Anianias and Sapphira in Jerusalem). In each case, believers are sinning not just against themselves, but against the respective body of congregants (or fellow believers) in the wider collective sense.
Thus, on the one hand, believers are to forgive their fellow believers “seventy times seven” when these sins are committed by one individual against another (Matt 18:21-22): in this regard we “bear the burdens of others” (Gal 6:1-2), and therefore intercede for one another before the Lord. However, whenever such sins become the immediate concern of the spiritual health of believers (in the plural), then the matter becomes one of accountability. If the errant believers do not repent, the apparent and inevitable result is intense suffering administered by the Lord, which will eventuate in physical death.
The context of 1 John 5:16 appears to be parallel to James 5:13-18, which provides more contrasting light and background. That is, James appears to address believers who are (a) suffering, (b) who are cheerful, and finally (c) believers who are not just suffering, but dying of sickness.
James 5:13-18 (NASB)
13 Is anyone among you suffering? Then he must pray. Is anyone cheerful? He is to sing praises. 14 Is anyone among you sick? Then he must call for the elders of the church and they are to pray over him, anointing him with oil in the name of the Lord; 15 and the prayer offered in faith will restore the one who is sick, and the Lord will raise him up, and if he has committed sins, they will be forgiven him. 16 Therefore, confess your sins to one another, and pray for one another so that you may be healed. The effective prayer of a righteous man can accomplish much. 17 Elijah was a man with a nature like ours, and he prayed earnestly that it would not rain, and it did not rain on the earth for three years and six months. 18 Then he prayed again, and the sky poured rain and the earth produced its fruit.
While believers who are dying of sickness are suffering, James appears to be making a distinction between believers who suffer (and therefore he directs them to pray), and believers who are dying of sickness, but who also may need special intervention and forgiveness for recovery. The mention of Elijah makes the suggestion that some (not all) believers dying of sickness may be suffering “the sin that leads to death.”
According to the Hebrew Bible, Elijah had witnessed the apostasy and sexual immorality of King Ahab and Jezebel (1 Ki 16:33), who in turn misled the people of whom all but 7,000 were apostate (1 Ki 19:18). Elijah therefore declared that no rain would fall from heaven, and, accordingly, no rain fell from heaven (1 Ki 17:1). The people then repented after Elijah’s showdown with the priests of Baal (1 Ki 18:36-40), and at that time Elijah prayed for the rain to return, and it rained from heaven.
In other words, what sins that were retained on earth were retained in heaven. Elijah prayed that rain should not fall, and no rain fell from heaven. What was loosed on earth then resulted in the loosening of rain from heaven--Elijah prayed as the context of James indicates. The idea thus emerges from the Hebrew Bible into the Christian New Testament.
Matthew 16:19 (NASB)
19 I will give you the keys of the kingdom of heaven; and whatever you bind on earth shall have been bound in heaven, and whatever you loose on earth shall have been loosed in heaven.
In other words, as seen by James's illustration of Elijah, binding and loosening have to do with accountability. For example, when Ananias and Sapphira lied to Peter regarding their financial contribution to the congregation, they dropped dead. Because their sin was open and obvious to all, the sin was against the collective Body of Christ: that is, their sin was “lying against the Holy Spirit” (Acts 5:1-11). On another occasion, when the errant believer in Corinth had an open immoral sexual relationship with his father’s wife, Paul declared that this believer was introducing “leaven” the congregation, and therefore he (Paul) handed this errant believer over to Satan (1 Cor 5:1-8). In Paul’s second epistle to the Corinthians, one errant believer (same immoral Christian?) appears to have been forgiven by his fellow believers, and so what was “loosed on earth” was therefore “loosed in heaven.”
2 Cor 2:6-10 (NASB)
6 Sufficient for such a one is this punishment which was inflicted by the majority, 7 so that on the contrary you should rather forgive and comfort him, otherwise such a one might be overwhelmed by excessive sorrow. 8 Wherefore I urge you to reaffirm your love for him. 9 For to this end also I wrote, so that I might put you to the test, whether you are obedient in all things. 10 But one whom you forgive anything, I forgive also; for indeed what I have forgiven, if I have forgiven anything, I did it for your sakes in the presence of Christ,
Another example is the “Jezebel” in Thyatira, who like her counterpart in the days of Elijah the Prophet, had misled the people into false teaching and sexual immorality (Rev 2:19-29). The result was that the Lord Jesus threw her “on a bed of sickness” with the intent that she repent of her sins (Rev 2:22). In other words, she and her cohorts were sinning against the collective Body of Christ (as represented in Thyatira), and therefore these sins “were leading to death.”
Finally, there is Hymenaeus and Alexander, whom the Apostle Paul handed over to Satan “that they...be taught not to blaspheme” (1 Tim 1:20). Hymenaeus also appears to have been a false teacher (2 Tim 2:17), and so both he and/or Alexander appear to have been prominent in the local congregation where Timothy served. In other words, these men were sinning against the collective body of believers, and therefore Paul did not release them from accountability (binding on earth = binding in heaven).
In conclusion, believers are to forgive their fellow believers “seventy times seven” when these sins are committed by one individual against another (Matt 18:21-22): in this regard we “bear the burdens of others” (Gal 6:1-2), and therefore intercede for one another before the Lord. However, whenever such sins become the concern of believers in the plural, the matter then becomes one of accountability.
1 John 5:16-17 (NASB)
16 If anyone sees his brother committing a sin not leading to death, he shall ask and God will for him give life to those who commit sin not leading to death. There is a sin leading to death; I do not say that he should make request for this. 17All unrighteousness is sin, and there is a sin not leading to death.
All sins are unfortunate and undesirable, but sins against the Body of Christ “lead to death.” Therefore when sins become the direct concern of more than one believer, then such sins “lead to death” – that is, believers hold other believers accountable before the Lord (for specific New Testament examples, please see Rom 16:17-18; 2 Thess 3:6; 2 Thess 3:14; 2 Jn 1:10). By holding other believers accountable before the Lord (“retaining sins on earth”), the outlook and expectation are that the Lord’s discipline is going to lead them to repent and therefore be healed/restored to the fellowship of believers (2 Cor 7:10).