The key to 'The Parable of the Unjust Judge' lies at its entrance, and it is "that men ought always to pray, and not to faint". A quick check of our favourite Concordance or Lexicon will show us that the word translated "faint" is used six times in the New Testament. On four of those occasions (Lk 18.1; 2 Cor 4.1, 16; Eph 3.13), in the Authorised Version, it is translated "faint", and it is twice rendered "weary" (Gal 6.9; 2 Thess 3.13). Having read each of those references, in their context, we would readily understand that the Lord was teaching the necessity for prayer to be made with unflagging energy.
The setting of the parable is relevant to conditions in the 21st century. The Lord had been speaking to the Pharisees about the coming of the Kingdom of God, and how that, prior to its public manifestation, there would be spiritual and moral declension until conditions in the world were like those in the days of Noah and of Lot (Lk 17.20-30). There can be little doubt that those conditions are ripening fast in our own day. The particular background to the parable is one of rampant social injustice, and the activities of a judge "which feared not God, neither regarded man" (18.2). Seeing that the judge did not fear God, it is hardly surprising that he had no regard for his fellow men, nor for their entitlement to justice. How oft we lament today the frequent miscarriages of natural justice, often because the law has been manipulated by appointed custodians 'who fear not God'. This age-old problem was bemoaned by the writer of Ecclesiastes who said "And moreover I saw under the sun the place of judgment, that wickedness was there; and the place of righteousness, that iniquity was there" (3.16). Every nation, society and tribe in the world recognises the need for laws to be passed and enforced. The evenness and equity of each legal system will depend directly on the godliness of that society and those who lead it. Ironically, the whole world longs for justice whilst persisting in its rejection of the only Man who can give it to them. David, by the Spirit, looked off to the millennial reign of the Lord Jesus and said "And he shall judge the world in righteousness, he shall minister judgment to the people in uprightness. The Lord also will be a refuge for the oppressed, a refuge in times of trouble" (Ps 9.8-9).
The widow was one of the "oppressed" of whom David spoke, her low social status and poverty barring her from access to the corrupt judge. He, in turn, lacked all compassion and could not have cared less for the woman's cause. However, her incessant calling upon him, and refusal to be dismissed, eventually persuaded the judge to attend to her. She had not stirred some deep-seated sense of justice or kindness on the part of the judge; far from it. Rather, her refusal to be ignored had become a source of irritation to him, so for his own selfish ends he heard her case.
The lessons concerning prayer in the parable do not come from comparing the widow to believers, and the unjust judge to God, but from contrasting these things. Israel was not a 'widow' without status, but was wedded to Jehovah (Jer 3.14) and "the apple of his eye" (Deut 32.10). Neither was there any comparison between the heartless, venal judge and the God of Israel whose love for His people was so evident. No, it is through contrast that we learn the lesson. If the lowly widow, by sheer persistence, could eventually move the uncaring judge to hear her, how much more would a loving God incline His ear to His beloved people? Perseverance in prayer tests our sincerity and faith but, thankfully, we never need to persuade our God to listen to our cause. Our situation is more blessed even than that of Israel, for we have a great High Priest who ever lives to make intercession for us (Heb 7.25). Never fear, dear child of God, "thy prayer is heard" (Lk 1.13).