John Calvin Commentary Acts 4:21

"And they, when they had further threatened them, let them go, finding nothing how they might punish them, because of the people; for all men glorified God for that which was done." — Acts 4:21 (ASV)

And when they had threatened them. And this is the outcome of sedition: that the wicked do not cease to breathe out their fury, yet they are bridled by the secret power of God, so that they do not know how to do any harm. How is it that, being content with threats, they do not also rage against their bodies, except because the power of God binds them like a chain?

It is not that the fear of God prevails with them, for it is respect for the people alone that hinders them; but the Lord binds them with his bonds, though they are ignorant of it.

Luke commends to us the providence of God in preserving his children. And though it is hidden from the wicked, yet we may behold it with the eyes of faith. Furthermore, the wonderful counsel of God shows itself here, in that the glory of Christ is furthered by those who are his most deadly enemies.

For when the priests assemble, it is not done without great rumor. Everyone waits for some rare and unique event; the apostles depart, having been set free and acquitted. Therefore, the adversaries are not only vanquished, but they confirm the gospel against their will.

Nevertheless, it is important for us to note again that the faithful achieve victory in such a way that they are always humbled under the cross.

For they are threatened again, and strictly charged that they no longer teach in the name of Christ. Therefore, they do not gain the upper hand in such a way as to avoid triumphing, except that this triumph is exclusively under the reproach of the cross.

When Luke says that they all glorified God, he notes the fruit of the miracle now for the second time, although it may be that they were not all brought to the perfect end.

For the person who is touched with a sense of the power of God, and who does not come to Christ, nor has his faith confirmed by the miracle, remains, as it were, midway. Yet this was something, though not everything: that the power of God was acknowledged in the healing of the man, so that the adversaries, being ashamed, ceased from their fury, or at least drew back a little.