The following is an excerpt from The MacArthur New Testament Commentary on 1 John 5.

This is the confidence which we have before Him, that, if we ask anything according to His will, He hears us. And if we know that He hears us in whatever we ask, we know that we have the requests which we have asked from Him. 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. All unrighteousness is sin, and there is a sin not leading to death. (5:14–17)

As noted above, the full experience of eternal life awaits Christians in heaven. But though they have not yet entered into their eternal inheritance (cf. 1 Peter 1:4), they have access to all of God’s resources through prayer. Parresia (confidence) literally means “freedom of speech” (cf. the discussion of 3:21 in chapter 13 of this volume). It can also be translated “boldness” (Acts 4:31), or “openness” (Acts 28:31). The phrase translated before Him has the sense of “in His presence.” Through Jesus Christ believers have “boldness and confident access” (Eph. 3:12) to God that enables them to “draw near with confidence to the throne of grace, so that [they] may receive mercy and find grace to help in time of need” (Heb. 4:16).

The sure promise of God is that when believers boldly and freely come to Him with their requests, He will hear and answer. If we ask anything according to His will, John wrote, He hears us. And if we know that He hears us in whatever we ask, we know that we have the requests which we have asked from Him. Hearing in this context refers to more than merely God’s being aware of believers’ requests; it also means that He grants the requests which we have asked from Him. That is nothing less than a blank check to ask God for anything, but it comes with one important qualifier: the requests must be according to His will.

To pray according to God’s will assumes first of all being saved. God is not obligated to answer the prayers of unbelievers. He may choose to do so when it suits His sovereign purposes, but God does not obligate Himself to any unbeliever. John illustrated this principle when he wrote earlier in this epistle, “Beloved, if our heart does not condemn us, we have confidence before God; and whatever we ask we receive from Him, because we keep His commandments and do the things that are pleasing in His sight” (3:21–22). The Lord Jesus Christ made a similar statement, recorded in John 15:7: “If you abide in Me, and My words abide in you [the definition of a genuine believer], ask whatever you wish, and it will be done for you” (cf. v. 16). Only believers, those who obey God’s commandments, can have the certainty that He will answer their prayers.

Praying according to God’s will also means confessing sin. The psalmist wrote in Psalm 66:18, “If I regard wickedness in my heart, the Lord will not hear” (cf. 1 Peter 3:7).

Again, the Lord’s promise in John 14:13–14 affirms the requirement of praying according to God’s will: “Whatever you ask in My name, that will I do, so that the Father may be glorified in the Son. If you ask Me anything in My name, I will do it.” To pray in Jesus’ name is to pray consistent with who He is, with the goal of bringing Him glory. It is to follow the pattern of His model prayer: “Your kingdom come. Your will be done, on earth as it is in heaven” (Matt. 6:10), and His example of humble submission to the Father’s will when He prayed in Gethsemane, “Father, if You are willing, remove this cup from Me; yet not My will, but Yours be done” (Luke 22:42). The goal of prayer is not to gratify our selfish desires (cf. James 4:3), but to align our wills with God’s purposes.

Praying according to God’s will not only brings glory to the Son, but also joy to believers. “Truly, truly, I say to you,” Jesus said, “if you ask the Father for anything in My name, He will give it to you. Until now you have asked for nothing in My name; ask and you will receive, so that your joy may be made full” (John 16:23–24). When obedient believers delight themselves in the Lord, He will plant the desires in their hearts for what glorifies Him (Ps. 37:4), and those desires will control their prayers. God’s answers to those prayers will glorify Him, bring believers’ wills into line with His purposes, and fill them with joy.

At first glance, verse 16 appears to introduce an abrupt change of subject. But upon further consideration, the connection of verses 16 and 17 to verses 14 and 15 becomes clear. By giving one important exception, John illustrates in a contrasting manner the extent of God’s promise to answer prayer. When a believer sees a brother (a real or professing believer) committing a sin not leading to death, the apostle writes, he shall ask and God will for him give life to those who commit sin not leading to death. On the other hand, there is a sin leading to death, and the apostle did not advise Christians to make request for this sin.

Evidently John and his readers knew what the sin leading to death was, since no explanation is given, but its exact meaning is difficult for us to determine. Two possibilities present themselves.

First, the sin in question may be that of a non-Christian leading to eternal death. In that case it would be a final rejection of Jesus Christ, such as that committed by those who attributed His miracles to the power of Satan (Matt. 12:31–32). Such ultimate apostasy is unforgivable, as Jesus declared:

Therefore I say to you, any sin and blasphemy shall be forgiven people, but blasphemy against the Spirit shall not be forgiven. Whoever speaks a word against the Son of Man, it shall be forgiven him; but whoever speaks against the Holy Spirit, it shall not be forgiven him, either in this age or in the age to come. (Matt. 12:31–32)

Praying for the restoration of such people to the fellowship from which they have departed (1 John 2:19) is futile, because “it is impossible to renew them again to repentance, since they again crucify to themselves the Son of God and put Him to open shame” (Heb. 6:6). John did not forbid prayer for such people, since it is impossible to know who they are. The apostle merely stated that prayer for them will not be answered; God has already made the final decision about their future. Supporting the view that John is referring to unbelievers is the present tense of the participle hamartanonta (“sinning”; the Greek text literally reads “If anyone sees his brother sinning a sin …”); John elsewhere in this epistle uses the present tense to describe the habitual sins that characterize unbelievers (e.g., 3:4, 6, 8; 5:18).

Another possibility is that John is not referring to an unbeliever, but to a believer. According to this view, the sin leading to death refers to a Christian’s sin that is so serious that God takes the life of the one committing it. He put to death Ananias and Sapphira when they lied to the Holy Spirit in front of the church (Acts 5:1–11). Paul wrote to the Corinthians concerning those who were abusing the Lord’s Table, “For this reason many among you are weak and sick, and a number sleep [have died]” (1 Cor. 11:30). The sin is not one particular sin, but any sin that the Lord determines is serious enough to warrant such severe chastisement.

Both of the above views reflect biblical truth, and it is hard to be dogmatic as to which one John had in mind. In either case, John’s point is that prayer for those committing a sin leading to death will not result in the outcome that might otherwise be expected.

Although God mercifully does not immediately punish every sin with death, every sin is nonetheless a serious matter to Him. All unrighteousness is sin, John reminded his readers, even sin not leading to death. Every sin is a violation of His law and an affront to God, and is to be confessed (1:9; Ps. 32:5), forsaken (Prov. 28:13), and mortified (Rom. 8:13; Col. 3:5).