John Calvin Commentary Psalms 139:20

"For they speak against thee wickedly, And thine enemies take [thy name] in vain." — Psalms 139:20 (ASV)

Who have spoken of you wickedly. He indicates the extent to which the wicked proceed when God spares them and refrains from punishing them. They not only conclude that they may commit any crime without punishment, but they also openly blaspheme their Judge.

He takes notice of their speaking wickedly, meaning that they make no effort to disguise their sin with plausible excuses. Unlike those who, having some shame left, will exercise a certain restraint in their language, these individuals make no secret of the contempt they have for God.

Regarding the second clause, where he speaks of their taking God’s name falsely, some have interpreted this too narrowly in relation to their sin of perjury. Those come closer to the truth who consider that the wicked are spoken of as taking God’s name in vain when they imagine Him according to their own foolish ideas.

We see from experience that most people are ignorant of who God is and judge Him as dead rather than alive. Verbally, they all acknowledge Him to be judge of the world, but this acknowledgment amounts to nothing, as they immediately strip Him of His office of judgment. This is to take God’s name in vain, by tarnishing His glory and, in a way, deforming it.

But as name is not in the original, and נשא, nasa, means to lift up, or on high, I think we are justified in interpreting the passage to mean that they carried themselves with an arrogant and false pride. This elation or haughtiness of spirit is almost always connected with that petulance he had previously noted.

What other reason can be given for their expressing such poisonous bitterness against God than pride and forgetfulness—on the one hand, of their own insignificance as human beings, and on the other, of the power that belongs to the Lord? For this reason, he calls them God’s adversaries, for all who exalt themselves above the place they should occupy act like the giants who warred against heaven.