1 Corinthians 6:19-20
But let us hear also what they say, that from this also we may learn their lofty spirit. “There is a God in heaven able to deliver us:” they take no care for themselves, but even when about to be burned the glory of God is all their thought. For what they say comes to this, Lest perchance if we are burnt you should charge God with weakness, we now declare unto you accurately our whole doctrine. “There is a God in heaven,” not such as this image here on earth, this lifeless and mute thing, but able to snatch even from the midst of the burning fiery furnace. Condemn him not then of weakness for permitting us to fall into it. So powerful is He that after our fall, He is able to snatch us out again out of the flame. “But if not, be it known unto you, O king, that we will not serve your gods, nor worship the golden image which you have set up.” Observe that they by a special dispensation are ignorant of the future: for if they had foreknown, there would have been nothing wonderful in their doing what they did. For what marvel is it if when they had a guarantee for safety, they defied all terrors? Then God indeed would have been glorified in that He was able to deliver from the furnace: but they would not have been wondered at, inasmuch as they would not have cast themselves into any dangers. For this cause He suffered them to be ignorant of the future that He might glorify them the more. And as they cautioned (ἠσψαλίξοντο) the king that he was not to condemn God of weakness though they might be burnt, so God accomplished both purposes; the showing forth His own power and the causing the zeal of the children to appear more conspicuous.
From whence then arose their doubting and their not feeling confident that they should at all events be preserved? Because they esteemed themselves assuredly too mean, and unworthy of such a benefit. And to prove that I say not this upon conjecture; when they fell into the furnace, they bewailed themselves after this sort, saying, “We have sinned, we have done iniquity, we cannot open our mouth.” And therefore they said, “But if not.” But if they did not plainly say this, namely, “God is able to deliver us; but if he deliver us not, for our sin's sake He will not deliver us;” wonder not at it. For they would have seemed to the barbarians to be sheltering the weakness of God under the pretext of their own sins. Wherefore His power only is what they speak of: the reason they allege not. And besides, they were well disciplined not to be over-curious about the judgments of God.
With these words then, they entered into the fire; and they neither cast insult upon the king, nor overturned the statue. For such should the courageous man be, temperate and mild; and that especially in dangers; that he may not seem to go forth to such contests in wrath and vain-glory; but with fortitude and self-possession. For whoso deals insolently undergoes the suspicion of those faults: but he that endures, and is forced into the struggle, and goes through the trial with meekness, is not only admired as brave, but his self-possession also and consideration cause him to be no less extolled. And this is what they did at that time; showing forth all fortitude and gentleness, and doing nothing for reward nor for recompense or return. “'Though He be not willing 'so it stands' to deliver us, we will not serve your gods:' for we have already our recompense in that we are counted worthy to be kept from all impiety, and for that end to give our bodies to be burned.”
We then also having already our recompense, (for indeed we have it in that we have been vouchsafed the full knowledge of Him, vouch-safed to be made members of Christ,) let us take care that we make them not members of an harlot. For with this most tremendous saying we must conclude our discourse, in order that having the fear of the threat in full efficacy, we may remain purer than gold, this fear helping to make us so. For so shall we be able, delivered from all fornication, to see Christ. Whom God grant us all to behold with boldness at that day, through the grace and loving-kindness of our Lord Jesus Christ; to Whom be the glory, for evermore. Amen.
Source: Homilies on First Corinthians (New Advent)