In Luke 18:1-5, Luke records Jesus’ parable about the repeated appeals of a widow to an unrighteous judge. Jesus gave the parable to convey the necessity of continual prayer in the midst of circumstances that tend to make people lose heart (18:1). Since the widow persisted in her appeals to the judge that he avenge her against her adversary, he gave her the relief that she requested (18:2-5).
Christ demanded that His teaching concerning the words of this unrighteous judge be heard (18:6). He then emphatically asserted through the use of a rhetorical question that demands a positive answer that God, the righteous Judge, in stark contrast to the unrighteous judge in the parable, will certainly avenge His elect who are crying out to Him day and night (18:7a). In the same question, He also taught that God would do so in spite of delays in His response (18:7b).
Furthermore, He proceeded to declare directly that God would quickly give them justice (18:8a). Christ followed up with a question that points to the necessity of faith in God’s ultimate vindication of His own at the coming of the Son of Man (18:8b). The flow of thought in the passage shows that Christ, as the Son of Man, is the One who will execute that vengeance as the Father’s agent.
By giving this parable and its application, Christ validated appeals to God to avenge His own of their adversaries. The emphatic teaching in this parable strongly implies that believers’ crying out to the Father to avenge them of their oppressors is a righteous practice. Such appeals are in keeping with many similar appeals in the Old Testament (for example, Ps. 10) as well as related content in the New Testament (Rom. 15:31; 2 Thess. 3:2).
Furthermore, Christ’s teaching here accords with His own supreme commitment to entrust Himself in His sufferings to the Father as “the One who judges righteously” (1 Pet. 2:23; cf. Luke 23:46). Moreover, this parable underscores that through unfailing prayer to God, faith in Christ is essential for properly handling injustices that believers are powerless to overcome (cf. Acts 7:59-60). Luke’s inclusion of this account in his Gospel argues for the importance of this dimension of the scriptural teaching about Christ as God’s judicial delegate.
 Martyred saints in heaven cry out to God for Him to judge and avenge their blood on those who dwell on the earth (Rev. 6:10).
 “When the fullness of time has arrived, God will suddenly and without delay put an end to the distress into which His chosen ones will be plunged by a hostile and evil world. There is no doubt about the certainty that Jesus will come again and that God will then make the righteous cause of the faithful triumph completely and forever. . . . [At Christ’s coming], God’s own elect will still continually be praying to Him that justice should be done to them. . . . He concludes the parable with a powerful summons to His followers to maintain true belief in Him, through whom the Father will give final victory.” Geldenhuys, Luke, 447.
 Apart from its context, the use of Luke 18:1 as a proof text for encouraging perseverance in prayer, while of some value, does not furnish the people of God with the real substantive teaching of the passage. For example, although he makes many helpful remarks about prayer in general, Warren W. Wiersbe hardly deals with the teaching of the passage about God’s avenging His elect and makes no specific mention of the Son of Man. The Bible Exposition Commentary, 1:247-49.