1 John 5:16-17.— In the apostolic age, the power of working miracles was very common; and in this conclusion of his epistle St. John gives directions to the Christians, to whom that power was granted. They could not indeed work a miracle till they had an impulse of the Spirit to suggest to them that God would hear their prayer, and at their request miraculously cure the diseased. And St. John seems here to order them to wait for the impulse of the Spirit, before they attempted to work a miracle. Such Christian professors as experienced and lived the Christian life, were in no danger of falling under any remarkable divine judgment; but from 1 Corinthians 11:30. James 5:14; James 5:20 and this place, it appears, that some professed Christians behaved irregularly, and thereby drew down upon themselves some diseases, as judgments from God. Some were punished with diseases that ended in temporal death; others, whose offences were not so aggravated, and who truly repented, were to be miraculously cured, and their diseases not to end in death. In such cases, the Christians who had the power of working miracles, had a divine impulse to direct them to pray for their offending Christian brother; and when they so prayed, according to the will of God suggested to them in that manner, God, at their request, granted life unto their Christian brother, who had sinned a sin not unto death. After this, St. John takes notice of the advantages which Christians had above the rest of the world; and concludeswith cautioning them against falling into any act of idolatry, to which their heathen neighbours, who were then very numerous, would be likely enough to tempt them; and perhaps that is mentioned in this place, as having been one of the sins which had drawn down remarkable diseases upon some of the offending Christians. See ch. 1 John 3:22 and on James 5:15; James 5:20.
If any man see his brother sin, &c.— "If a Christian, by an impulse of the Spirit, perceives that any Christian brother has sinned such a sin as to draw down upon himself a disease which is not to end in death, but to be miraculously cured by him; then let him pray to God through Jesus Christ, and God, in answer to his prayer, will grant life and perfect health unto such Christian as hath sinned a sin which is not unto death. There is a sin which draws down a disease upon Christians, that is to end in death; I do not say or mean that any Christian shall pray for that; because in such a case God would not hear his prayer, nor miraculously cure his Christian brother at his request." Some by a sin unto death understand apostacy from the Christian religion.