John Calvin Commentary Genesis 18:25

"That be far from thee to do after this manner, to slay the righteous with the wicked, that so the righteous should be as the wicked; that be far from thee: shall not the Judge of all the earth do right?" — Genesis 18:25 (ASV)

Shall not the Judge of all the earth do right? He does not here teach God His duty, as if anyone should say to a judge, ‘See what your office requires, what is worthy of this place, what suits your character;’ but he reasons from the nature of God, that it is impossible for Him to intend anything unjust.

I grant that, in using the same form of speaking, the impious often murmur against God, but Abraham does far otherwise. For although he wonders how God should think of destroying Sodom, in which he was persuaded there was a number of good men, he yet retains this principle: that it was impossible for God, who is the Judge of the world and by nature loves equity—indeed, whose will is the law of justice and rectitude—to swerve in the least degree from righteousness. He desires, however, to be relieved from this difficulty with which he is perplexed.

So, whenever different temptations contend within our minds, and some appearance of contradiction presents itself in the works of God, if only our persuasion of His justice remains fixed, we will be permitted to pour into His bosom the difficulties that torment us, so that He may loosen the knots we cannot untie.

Paul seems to have taken from this passage the answer with which he represses the blasphemy of those who charge God with unrighteousness.

‘Is God unrighteous? Far from it, for how should there be unrighteousness with Him who judges the world?’ (Romans 3:5–6).

This method of appeal would not always avail among earthly judges, who are sometimes deceived by error, perverted by favor, inflamed with hatred, corrupted by gifts, or misled by other means to acts of injustice. But since God, to whom it naturally belongs to judge the world, is liable to none of these evils, it follows that He can no more be drawn aside from equity than He can deny Himself to be God.