I. What is the central thought of this parable? The answer to this question is obvious. The central thought of the parable is the advantage to be derived from importunity in prayer. And the general fact which the story conveys is this: with man importunity will succeed, when the power of justice or affection would wholly fail. No one, I suppose, can doubt that there are many cases in which this is true, and so far the parable presents no difficulty.
II. But it is quite otherwise when we come to ask What lesson is the parable meant to teach? What parallel is here drawn between the dealings of men with each other and the dealings of God with men? It is no merit, but a fault, in the selfish friend or the unjust judge, that importunity is needed to wring from them that which should have been given to love or justice. How can we argue that because importunity has succeeded with the selfish men, and that altogether by acting on their selfishness, it will therefore succeed with one whose nature is wholly different? A selfish man is teased into granting a request to save himself from personal annoyance. Does this afford any probability that an unselfish man can be similarly influenced. Yet certainly this seems to be the argument of the parable. Here is the only a fortioriargument drawn from the parable which appears to be admissible: we may expect importunate prayer to succeed better with God than with man, not because the means used is stronger in the one case than in the other, but because it has no resistance to overcome. Delay in granting the petition there may be; even ultimate refusal there may be; but both are dictated by the wise mercy of God; and the obstacles by which the selfishness of humanity blocks the way of the petitioner find no place with Him.
J. H. Jellett, The Elder Son and Other Sermons,p. 68.
Reference: Luke 18:7. Preacher's Monthly,vol. ii., p. 97.