Acts 14:22

“For what they set before themselves, first and foremost, was to do the work of an evangelist, and to teach the Word of God, in which, confirming the brethren, that they might continue in the faith, they said this also, "that we must out of much tribulation enter into the kingdom of God." For they sought not what was profitable for them, but that which was profitable for the many, that they might be saved, and that they might be enabled to say unto them many things conducing to this, that they might act suitably to the Word of God, "unless," as says the apostle, "the time should fail me in speaking."”

“"And he snatched me from all my tribulations." The just person's entire life is tribulation, "both straight and narrow the way," and "many are the tribulations of the just ones." Therefore the apostle elsewhere says that he has been "afflicted in every way," and here, that "we must enter the kingdom of God through many afflictions." God does rescue the holy from affliction, but he does so not by rendering them untested but by blessing them with endurance. For if "affliction brings about endurance, then endurance brings about an approved character." Whoever rejects affliction deprives himself of approval. Just as none is crowned who has no rival, so none can be pronounced worthy except through tribulations. Therefore, "he snatched me from all my tribulations," not by allowing me not to be afflicted but by granting with the test a way out, in order to be able to endure.”

“And the glutton is not pleased to hear the other things which have been written by Paul upon fortitude and asceticism, either when he recounteth his numerous fastings, or when he crieth out to his disciples, saying, "Ye are dead unto the world," or when he writeth, "It is good for a man not to eat flesh, and not to drink wine," or his exhortation, "Through many tribulations it is meet for a man to enter into the kingdom of God," or his saying, "God shall bring both the belly and the food to nought;" and the reading of these and such like passages the glutton considereth unnecessary, and he is not pleased even to hear them.”

“Let us not spare the destruction of our body, that our inner man may be renewed day by day. Let us not think anxiously about the pains and sicknesses which will befall us, but let us think that if things be not thus the wounds of the soul cannot be healed; let us be filled with joy in running our course, because it is known that we hasten after hope. Let us labour like sons of grace for the Father of truth, that we may be worthy of that inheritance which is filled with blessings, and is promised unto sons, and let us always remember the word of the Apostle, "By tribulation it is meet that we should enter the kingdom of God."”

“"Through many tribulations we must enter the Kingdom of God." Look: without labor and sorrows no one is justified. Therefore the gates leading to the Kingdom of Heaven the Lord also called narrow and strait (cf. Matt. 7:13), that is, full of hardships. But not every hardship or sorrow that one may encounter leads into the Kingdom of Heaven, but sorrow for the sake of faith in God.”