Haydock Catholic Bible Commentary
2Co 4:1 apostle, having in the last chapter shewn the excellence of his ministry above that of the law, proceeds to inform them of his own labours, &c. in order to destroy the credit which the false teachers had acquired amongst the Corinthians, and to caution them against any attempts that these teachers might make to destroy what had caused St. Paul so much trouble to effect. But he still refers all to God. As for these false teachers, what Churches had they founded? what persecutions have they endured? (Calmet)
2Co 4:3 apostle here brings another proof of the sincerity of his preaching, viz. the success with which it is attended: And he says, if there be any who have not yet received it, that is their own fault. For had they been as eager to receive it, as we have been to announce it to them, the whold world had long since been converted. (Theodoret)
In whom the God of this world hath blinded the minds of unbelievers. Thus the words are placed, both in the Latin and Greek text, so that the true God seems to be called the God of this world, as he is elsewhere called the God of heaven, the God of Abraham. God, says St. John Chrysostom, blinded, that is, permitted them to be blinded. Others translate, in whom God hat blinded the minds of the infidels of this world; so that this world may be joined with unbelievers, and not with God: and by the God of this world, some understand the devil, called sometimes the prince of this world, that is, of the wicked. (Witham)
In quibus Deus hujus sæculi excæcavit mentes infidelium, Greek: en ois o Theos tou aionos toutou etuphlose ta noemata ton apiston. St. John Chrysostom, Greek: om. e. p. 594. lin. 11. says, it should be read thus: Greek: anagnosteon, oti ton apiston tou aionos toutou, etuphlosen o theos  oemata.
The light to shine out of darkness. He alludes to what is related at the first creation, when God divided the light from darkness. (Genesis i. 4.) --- In the face of Christ Jesus, which may signify in the person of Christ, who was the true light enlightening every man, that comes into this world. (John i. 9.) (Witham)
We are straitened. This, by the Greek, seems the sense of the Latin word, which is taken to signify, one perplexed, and in a doubt. See John xiii. 22.; Acts xxv. 20.; Galatians iv. 20.) (Witham)
Aporiamur, Greek: aporoumenoi, from Greek: a and Greek: poros, transitus. See Mr. Legh.
That the life also of Jesus may be made manifest in our bodies, when we suffer, and undertake voluntary sufferings for his sake. (Witham)
Death worketh in us, when we are under persecutions, and dangers of death, and life in you, who live in ease and plenty. (Witham) --- The preaching of the gospel, which we undertake in such a disinterested manner, and which exposes us to so many dangers, is the case of death to us, but procures you all kinds of advantages. You tranquilly enjoy the fruit of our labour, though we do not envy you this happiness, because we hope one day to enjoy the reward of our labours. (Calmet)
We also believe, &c. That is, we have the like faith as David, when he spoke in that manner; we hope and believe, God will deliver us, or at least raise us up from the dead with Jesus. (Witham)
For all things, that we suffer, are for your sakes, that many may be brought to give thanks, and to praise God for eternity. This encourages us not to fail, nor faint in the cause of God, under these momentary and light tribulations, which mark in us above measure, an exceeding and eternal weight of glory. See the Greek text. (Witham)
Worketh. In the Greek, Greek: katergazetai, which the English Bible of the year 1577 falsely renders by prepareth, unwilling to allow, with the apostle, that tribulation worketh eternal glory. The ardour with which the apostle speaks is sufficient to inspire the most timid with courage. A life full of crosses, labours, persecutions, injuries, &c. he call momentary and light, if compared with the eternal, immense, and incomprehensible glory prepared for us. (St. Augustine) --- All earthly substance, compared with the happiness of heaven, is rather a loss than a gain. This life, when put in comparison with that to come, is rather a death than life. (St. Gregory in Evangel.)