John Calvin Commentary Acts 8:4

"They therefore that were scattered abroad, went about preaching the word." — Acts 8:4 (ASV)

And they were scattered abroad. Luke declares in this passage also, that it came about by the wonderful providence of God, that the scattering of the faithful would bring many to the unity of faith; thus the Lord brings light out of darkness, and life out of death.

For the voice of the gospel, which was heard previously in one place only, now sounds everywhere.

Meanwhile, we are taught by this example that we must not yield to persecutions, but rather be encouraged to courage.

For when the faithful fled from Jerusalem, they were not afterwards discouraged by exile, by their present miseries, or by any fear that they might degenerate into slothfulness; rather, they were as ready to preach Christ even in the midst of their calamity as if they had never suffered any trouble.

Moreover, Luke seems to note that they led a wandering life, changing their lodgings often.

Therefore, if we desire to be counted their brothers, let us urge ourselves forward so diligently, that no fear or bitterness of the cross discourage us; but that we rather press on in professing our faith, and that we never be weary of advancing the doctrine of Christ. For it is an absurd thing that exile and flight, which are the first exercises of martyrdom, should make us silent and fainthearted.