4 Well, then, if it is evident from whom persecution proceeds, we are able at once to satisfy your doubts, and to decide from these introductory remarks alone, that men should not flee in it. For if persecution proceeds from God, in no way will it be our duty to flee from what has God as its author; a twofold reason opposing; for what proceeds from God ought not on the one hand to be avoided, and it cannot be evaded on the other. It ought not to be avoided, because it is good; for everything must be good on which God has cast His eye.
And with this idea has perhaps this statement been made in Genesis, “And God saw because it is good;” not that He would have been ignorant of its goodness unless He had seen it, but to indicate by this expression that it was good because it was viewed by God. There are many events indeed happening by the will of God, and happening to somebody's harm. Yet for all that, a thing is therefore good because it is of God, as divine, as reasonable; for what is divine, and not reasonable and good?
What is good, yet not divine? But if to the universal apprehension of mankind this seems to be the case, in judging, man's faculty of apprehension does not predetermine the nature of things, but the nature of things his power of apprehension. For every several nature is a certain definite reality, and it lays it on the perceptive power to perceive it just as it exists. Now, if that which comes from God is good indeed in its natural state (for there is nothing from God which is not good, because it is divine, and reasonable), but seems evil only to the human faculty, all will be right in regard to the former; with the latter the fault will lie.
In its real nature a very good thing is chastity, and so is truth, and righteousness; and yet they are distasteful to many. Is perhaps the real nature on this account sacrificed to the sense of perception? Thus persecution in its own nature too is good, because it is a divine and reasonable appointment; but those to whom it comes as a punishment do not feel it to be pleasant. You see that as proceeding from Him, even that evil has a reasonable ground, when one in persecution is cast out of a state of salvation, just as you see that you have a reasonable ground for the good also, when one by persecution has his salvation made more secure.
Unless, as it depends on the Lord, one either perishes irrationally, or is irrationally saved, he will not be able to speak of persecution as an evil, which, while it is under the direction of reason, is, even in respect of its evil, good. So, if persecution is in every way a good, because it has a natural basis, we on valid grounds lay it down, that what is good ought not to be shunned by us, because it is a sin to refuse what is good; besides that, what has been looked upon by God can no longer indeed be avoided, proceeding as it does from God, from whose will escape will not be possible.
Therefore those who think that they should flee, either reproach God with doing what is evil, if they flee from persecution as an evil (for no one avoids what is good); or they count themselves stronger than God: so they think, who imagine it possible to escape when it is God's pleasure that such events should occur.
Source: De Fuga in Persecutione (New Advent)