I John 5:16 “If any man see his brother sin a sin which is not unto death, he shall ask, and he shall give him life for them that sin not unto death. There is a sin unto death: I do not say that he shall pray for it. 17 All unrighteousness is sin: and there is a sin not unto death.”
The word “sin” literally means to ‘miss the mark’. The ‘mark’ is obedience to God’s Commandments; thus, to “sin” is to disobey God. The effect of sin is separation from the blessings and benefits of God. Isaiah told Israel, “your iniquities have separated between you and your God, and your sins have hid his face from you, that he will not hear” (Isaiah 59:2). This separation is a kind of “death”, for the word “death” literally means to be separated from. When God told Adam, “in the day that thou eatest thereof thou shalt surely die” (Genesis 2:17), He meant what He said; for, when Adam disobeyed God, he immediately died to his innocence, peace, joy, and to the benefits of the Garden (Genesis 3); furthermore, he placed himself on a course of decline that led to his natural death. The overriding message here is that when we see a “brother sin”, we are to pray for him, asking God to extend mercy to him. The need for such prayer is easy to recognize; for, we can readily see the pain and misery that “sin” brings to the life of those who disobey God. “Life” is the opposite of “death”; thus, when this dreadful sin’s “death” (separation) is reversed, there is life again; that is, there is again joy and peace for the once troubled soul. Thus, we are charged to pray for our Brethren who are plagued by sin’s “death”, that the joy of “life” in Christ will be restored to them. The exception is that we are not instructed to pray for the “sin unto death”; which is a “sin” so grievous to God that there is no relief from it in this present life, the pain and suffering of it sets upon the sinner until they die a natural death. Otherwise, we are to pray for our Brethren who “sin”; and by their “sin”, they bring great suffering upon themselves in this present life!