Athanasius of Alexandria : Now my beloved, our will ought to keep pace with the grace of God and not fall short; lest while our will remains idle, the grace given us should begin to depart, and the enemy finding us empty and naked, … as was the case with him spoken of in the Gospel, from whom the devil went out. … For the departure from virtue gives place for the entrance of the unclean spirit. — FESTAL LETTERS 3:3 Augustine of Hippo : "Come forth out of Babylon." If we take the command of the prophet in a spiritual sense, it means that we should fly from the city of this world, from the fellowship of wicked angels and wicked [people], with the feet of that faith that works through love, and we should press onward unceasingly toward the living God. — City of God 18.18 Jerome : (Verse 20, 21, 22.) Go out of Babylon, flee from the Chaldeans; proclaim it with a shout of joy, make it heard, proclaim it to the ends of the earth, and say: The Lord has redeemed his servant Jacob. They did not thirst when he led them through the desert; he made water flow for them from the rock; he split the rock and water gushed out. There is no peace for the wicked, says the Lord. Those above in that place, where it is written: I have spoken and called it; I have brought him and his way is straight; they understand it concerning Cyrus and Darius; even this refers to those times when the people went out of Babylon and fled from the Chaldeans, and they were redeemed by their Lord God. This also, which is said: They did not thirst in the desert when he led them out, he brought water from the rock for them; and he split the rock, and water flowed. Although they cannot teach that it was fulfilled according to history; for they did not come through the desert under Zerubbabel and Ezra, and the split rock provided them water, as is narrated to have happened to those coming out of Egypt: however, they testify hyperbolically that it was fulfilled in likeness to the previous happiness, when they came through the desert of nations into Judaea, and were liberated from captivity. And so, they say, it is not about Christ, but about Cyrus that it is prophesied: There is no peace for the wicked, says the Lord. And it is understood to mean that perfect happiness will not exist except under Christ, which is reserved for the last time. Moreover, those who interpret this more truly and rightly refer it to the coming of the Savior, of whom it is said: He has sent me to announce good news to the poor, to proclaim freedom for prisoners. They understand it as an exhortation for those who proclaim the Gospel of the Lord Savior himself, so that we may come out of Babylon, that is, the confusion of this world, and flee from the Chaldeans, of whom it is often said: For the Lord has redeemed his servant Jacob with his precious blood and led him through the desert of the world and split the rock to give water. The Apostle speaks excellently: But the rock was Christ (I Cor. X, 4). However, the divine word is divided and divided into many parts, so that we may receive it in parts, since we cannot receive it all at once. And so that it may not be thought that this preaching is directed to all the descendants of Jacob and not only to those who will believe through the Apostles, it is added and connected: There is no peace for the wicked, says the Lord, namely those who have remained in their original error; those who do not deserve to drink from the rock. Whose side pierced with a spear, flowed with water and blood (John 19), giving us baptism and martyrdom. — Commentary on Isaiah