John Calvin Commentary Luke 18:9

"And he spake also this parable unto certain who trusted in themselves that they were righteous, and set all others at nought:" — Luke 18:9 (ASV)

Christ now gives directions about another virtue, which is necessary for acceptable prayer. Believers must not come into the presence of God except with humility and abasement. No disease is more dangerous than arrogance; and yet all have it so deeply fixed in the marrow of their bones that it can scarcely be removed or eradicated by any remedy.

It is undoubtedly strange that people should be so foolish as to venture to raise their crests against God and to plead their own merits before Him. Though people are carried away by their ambition, yet when we come into the presence of God, all presumption ought to be laid aside. And yet everyone thinks that they have sufficiently humbled themselves if they only present a hypocritical prayer for forgiveness. Therefore, we infer that this warning which our Lord gives was far from being unnecessary.

Christ alludes to two faults which He intended to condemn: wicked confidence in ourselves and the pride of despising our brothers and sisters, one of which springs from the other. It is impossible that one who deceives themselves with vain confidence should not lift themselves up above their brothers and sisters. Nor is it surprising that it should be so; for how could that person not despise their equals, who boasts against God Himself?

Everyone who is puffed up with self-confidence wages open war with God, with whom we cannot be reconciled in any other way than by denying ourselves; that is, by laying aside all confidence in our own virtue and righteousness, and relying on His mercy alone.