Luke 18:1-18, the dogged nagging of the persistent widow before the unjust judge, can be one of the more confusing parables that Jesus told.
One clue that can help our interpretation is to remember that Jesus often used a fortiori arguments—arguments that reason from the lesser to the greater.
The Apostle Paul uses this form of “If X, how much more Y” in his didactic teaching (see, e.g., 2 Corinthians 3:7-9; Romans 5:9-10), whereas Jesus tends to use more earthly, everyday images to make this point about God’s character and car. For example:
“If you then, who are evil, know how to give good gifts to your children, how much more will your Father who is in heaven give good things to those who ask him!
“But if God so clothes the grass of the field, which today is alive and tomorrow is thrown into the oven, will he not much more clothe you, O you of little faith?” (Matthew 6:30)
“Which one of you who has a sheep, if it falls into a pit on the Sabbath, will not take hold of it and lift it out? Of how much more value is a man than a sheep! So it is lawful to do good on the Sabbath.” (Matthew 12:11-12)
With that in mind, we might gain a little clarity on Jesus’s parable of the persistent widow and the unjust judge:
And he told them a parable to the effect that they ought always to pray and not lose heart.
“In a certain city there was a judge who neither feared God nor respected man.
And there was a widow in that city who kept coming to him and saying,
‘Give me justice against my adversary.’
For a while he refused, but afterward he said to himself,
‘Though I neither fear God nor respect man, yet because this widow keeps bothering me, I will give her justice, so that she will not beat me down by her continual coming.'”
And the Lord said,
“Hear what the unrighteous judge says.
And will not God give justice to his elect, who cry to him day and night?
Will he delay long over them?
I tell you, he will give justice to them speedily.
Nevertheless, when the Son of Man comes, will he find faith on earth?”
(Luke 18:1-8 ESV)
Craig Blomberg, in Interpreting the Parables (IVP, 1990), 273, gets to the heart of what Jesus is teaching:
The parable teaches both that (1) God will hear and answer the cries of his people against injustice by again sending the Son of man to earth, although they cannot be sure of the timing, and that, therefore, (2) we must persist in faithful petition for the consummation of the kingdom.
In other words, Jesus is teaching the opposite of what we tend to think about this parable. Yes, we should be like the persistent widow (continually coming to him, crying to him day and night for justice), but how much more can we do this when we have a judge who loves justice and will settle all accounts speedily.
To drive home the original imagery of the “lesser than” part of Jesus’s argument, here’s a trailer for one of the Modern Parables, reimagining the unjust judge and the persistent widow in a more contemporary context: