John Calvin's Bible Commentary
Jeremiah 20:11
Here the Prophet sets up God’s aid against all the plottings formed against him. However, then, might perfidious friends on one hand try privately to entrap him, and open enemies might on the other hand publicly oppose him, he yet doubted not but that God would be a sufficient protection to him. And we ought to act exactly in the same manner, whenever Satan rouses the wicked against us to oppose us either by secret artifices or by open cruelty; God alone must be, as they say, our brazen wall. But we must first know that he stands on our side; for the power of God can avail nothing to animate us, except we be firmly persuaded of this truth, that he is on our side. And how this confidence can be obtained, we shall presently see.
He says, that his persecutors would fall, so that they would not prevail, but be ashamed We see how many persecuted the holy man, and also with what arms they were furnished; for they possessed great power, and were also endued with guiles and intrigues. But the Prophet was satisfied with the help of God alone, and boldly concluded, that they would fall; for it could not be but that God would prove victorious. Whenever, then, we fight with the world and the devil and his slaves, this ought in the first place to come to our minds, that God stands on our side to defend our cause and to protect our safety. This being settled, we may then boldly defy both the artifices and the violence of all enemies; for it cannot be but that God will scatter, lay prostrate, overwhelm, and reduce to nothing all those who fight against him.
He further says that their reproach would be perpetual, and would never come to oblivion We have seen already that the Prophet was loaded with many reproaches; but whenever God suffers his servants to be exposed to the curses of the wicked, he in due time aids them; and therefore we ought fully to expect that he will shortly dissipate, as mists, such calumnies. As then God, according to what is said in Psalms 37:6, brings forth the innocency of the godly like the dawn, which in a moment appears while the earth seems buried in darkness, so the Prophet now says that on the other hand the reproach with which God will cover all the wicked will be perpetual. (14) It now follows, —
11.But Jehovah is with me as a terrible warrior; Therefore my persecutors shall stumble, And shall not prevail: They have become exceedingly ashamed, Because they have not succeeded; A perpetual shame! It shall not be forgotten.
The last two lines are according to what Horsley suggests. “A terrible warrior” is rendered by the Sept. , “a strong combatant, μαχητὴς ἰσχύων;” by the Vulg. , “a brave warrior, bellato fortis, by the Syr. , “the strongest giant;” and by the Arab. , “the strongest help.” — Ed