The Early Church Fathers
Clicking on the Early Church Father's name or on the work will take you to The Catholic Encyclopedia at NewAdvent.org
It is in vain, then that some, indeed very many, make moan over the eternal punishment, and perpetual, unintermitted torments of the lost, and say they do not believe it shall be so;…But let them suppose, if the thought gives them pleasure, that the pains of the damned are, at certain intervals, in some degree assuaged. For even in this case the wrath of God, that is¸their condemnation (for it is this, and not any disturbed feeling in the mind of God that is called His wrath, abides upon them that is, His wrath, though it still remains, does not shut up His tender mercies; though His tender mercies are exhibited, not in putting an end to their eternal punishment, but in mitigating, or in granting them a respite from their torments.
On Faith, Hope, and Love (Enchiridion), Chapter 112
St. Clement of Alexandria
Do not you judge who is worthy or who is unworthy. For it is possible you may be mistaken in your opinion. As in the uncertainty of ignorance it is better to do good to the underserving for the sake of the deserving, than by guarding against those that are less good to fail to meet in with the good. For though sparing, and aiming at testing, who will receive meritoriously or not, it is possible for you to neglect some that are loved by God; the penalty for which is the punishment of eternal fire.
Who is the Rich Man that shall be Saved?, Chapter 33
St. Cyril of Jerusalem
For this body shall be raised, not remaining weak as now; but raised the very same body, though by putting on incorruption it shall be fashioned anew,--as iron blending with fire becomes fire, or rather as He knows how, the Lord who raises us. This body therefore shall be raised, but it shall abide not such as it now is, but an eternal body; no longer needing for its life such nourishment as now, nor stairs for its ascent, for it shall be made spiritual, a marvelous thing, such as we cannot worthily speak of. Then, it is said, shall the righteous shine forth as the sun, and the moon, and as the brightness of the firmament (Matthew 13:43; Daniel 12:3). And God, foreknowing men’s unbelief, has given to little worms in the summer to dart beams of light from their body, that from what is seen, that which is looked for might be believed; for He who gives in part is able to give the whole also, and He who made the worm radiant with light, will much more illuminate a righteous man. We shall be raised therefore, all with our bodies eternal¸ but not all with bodies alike: for if a man is righteous, he will receive a heavenly body, that he may be able worthily to hold converse with Angels; but if a man is a sinner, he shall receive an eternal body, fitted to endure the penalties of sins¸ that he may burn eternally in fire, nor ever be consumed. And righteously will God assign this portion to either company; for we do nothing without the body. We blaspheme with the mouth, and with the mouth we pray. With the body we commit fornication¸ and with the body we keep chastity. With the hand we rob, and by the hand we bestow alms; and the rest in like manner. Since then the body has been our minister in all things, it shall also share with us in the future the fruits of the past.
St. Ignatius of Antioch
Make no mistake, brethren; the corrupters of families will not inherit the kingdom of God. If, then, those are dead who do these things according to the flesh, how much worse if, with bad doctrine, one should corrupt the faith of God for which Jesus Christ was crucified. Such a man, for becoming contaminated, will depart into unquenchable fire; and will any one who listens to him.
Letter to the Ephesians, Chapter 16:1
St. Justin Martyr
And more than all other men are we your helpers and allies in promoting peace, seeing that we hold this view, that it is alike impossible for the wicked, the covetous, the conspirator, and for the virtuous, to escape the notice of God, and that each man goes to everlasting punishment or salvation according to the value of his actions. For if all men knew this, no one would choose wickedness even for a little, knowing that he goes to the everlasting punishment of fire; but would by all means restrain himself, and adorn himself with virtue, that he might obtain the good gifts of God, and escape the punishments.
The First Apology, Chapter 12
St. Justin Martyr
And we have learned that those only are deified who have lived near to God in holiness and virtue; and we believe that those who live wickedly and do not repent are punished to everlasting fire.
The First Apology, Chapter 21
St. Theophilus of Antioch
But read the prophetic Scriptures, and they will make your way plainer for escaping the eternal punishments, and obtaining the eternal prizes of God. For He who gave the mouth speech, and formed the ear to hear, and made the eye to see, will examine all things, and will judge righteous judgment, rendering merited awards to each. To those who by patent continuance in well-doing seek immortality, He will give life everlasting, joy, peace, rest, and abundance of good things, which neither has eye seen, nor ear heard, nor has it entered the heart of man to conceive (1 Corinthians 2:9). But to the unbelieving and despisers, who obey not the truth, but are obedient to unrighteousness, when they shall have been filled with adulteries and fornications, and filthiness, and covetousness, and unlawful idolatries, there shall be anger and wrath¸ tribulation and anguish, and at the last everlasting fire shall possess such men (Romans 2:8, 9).
To Autolycus, Chapter 1:14
Catechism for Mobile Devices (SCBorromeo.org)