The Early Church Fathers believed in purgatory and prayers for the dead.
Clement of Alexandria
The believer through discipline divests himself of his passions and passes to the mansion which is better than the former one, passes to the greatest torment, taking with him the characteristic of repentance for the faults he may have committed after baptism. He is tortured then still more, not yet attaining what he sees others have acquired. The greatest torments are assigned to the believer, for God’s righteousness is good, and His goodness righteous, and though these punishments cease in the course of the expiation and purification of each one, “yet” etc. (Patres Groeci. IX, col. 332 [A.D. 150-215]).
Origen
If a man departs this life with lighter faults, he is condemned to fire which burns away the lighter materials, and prepares the soul for the kingdom of God, where nothing defiled may enter. For if on the foundation of Christ you have built not only gold and silver and precious stones (I Cor., 3); but also wood and hay and stubble, what do you expect when the soul shall be separated from the body? Would you enter into heaven with your wood and hay and stubble and thus defile the kingdom of God; or on account of these hindrances would you remain without and receive no reward for your gold and silver and precious stones? Neither is this just. It remains then that you be committed to the fire which will burn the light materials; for our God to those who can comprehend heavenly things is called a cleansing fire. But this fire consumes not the creature, but what the creature has himself built, wood, and hay and stubble. It is manifest that the fire destroys the wood of our transgressions and then returns to us the reward of our great works. (Patres Groeci. XIII, col. 445, 448 [A.D. 185-232]).
Abercius
The citizen of a prominent city, I erected this while I lived, that I might have a resting place for my body. Abercius is my name, a disciple of the chaste shepherd who feeds his sheep on the mountains and in the fields, who has great eyes surveying everywhere, who taught me the faithful writings of life. Standing by, I, Abercius, ordered this to be inscribed; truly I was in my seventy-second year. May everyone who is in accord with this and who understands it pray for Abercius (Epitaph of Abercius [A.D. 190]).
Tertullian
That allegory of the Lord [Matt. 5:25-26] . . . is extremely clear and simple in its meaning . . . [beware lest as] a transgressor of your agreement, before God the judge . . . and lest this judge deliver you over to the angel who is to execute the sentence, and he commit you to the prison of hell, out of which there will be no dismissal until the smallest even of your delinquencies be paid off in the period before the resurrection. What can be a more fitting sense than this? What a truer interpretation? (The Soul 35 [A.D. 210]).
The faithful widow prays for the soul of her husband, and begs for him in the interim repose, and participation in the first resurrection, and offers prayers on the anniversary of his death (Monogamy 10 [A.D. 213]).
Cyprian
It is one thing to stand for pardon, another thing to attain to glory; it is one thing, when cast into prison, not to go out thence until one has paid the uttermost farthing; another thing at once to receive the wages of faith and courage. It is one thing, tortured by long suffering for sins, to be cleansed and long purged by fire; another to have purged all sins by suffering. It is one thing, in fine, to be in suspense till the sentence of God at the Day of Judgment; another to be at once crowned by the Lord (Letters 51[55]:20 [A.D. 253]).
Cyril of Jerusalem
Then we make mention also of those who have already fallen asleep: first, the patriarchs, prophets, apostles, and martyrs, that through their prayers and supplications God would receive our petition, next, we make mention also of the holy fathers and bishops who have already fallen asleep, and, to put it simply, of all among us who have already fallen asleep. For we believe that it will be of very great benefit to the souls of those for whom the petition is carried up, while this holy and most solemn sacrifice is laid out (Catechetical Lectures 23:5:9 [A.D. 350]).
John Chrysostom
Let us help and commemorate them. If Job’s sons were purified by their father’s sacrifice [Job l:5), why would we doubt that our offerings for the dead bring them some consolation? Let us not hesitate to help those who have died and to offer our prayers for them (Homilies on First Corinthians 41:5 [A.D. 392]).
Not in vain was it decreed by the apostles that in the awesome mysteries remembrance should be made of the departed. They knew that here there was much gain for them, much benefit. When the entire people stands with hands uplifted, a priestly assembly, and that awesome sacrificial victim is laid out, how, when we are calling upon God, should we not succeed in their defense? But this is done for those who have departed in the faith, while even the catechumens are not reckoned as worthy of this consolation, but are deprived of every means of assistance except one. And what is that? We may give alms to the poor on their behalf (Homilies on Philippians 3:9-10 [A.D. 402]).
Augustine
Temporal punishments are suffered by some in this life only, by some after death, by some both here and hereafter, but all of them before that last and strictest judgment. But not all who suffer temporal punishments after death will come to eternal punishments, which are to follow after that judgment (The City of God 21:13 [A.D. 419]).
