Prayer for the Dead

2 Maccabees 12:44-45
For if he were not expecting that those who had fallen would rise again, it would have been superfluous and foolish to pray for the dead. But if he was looking to the splendid reward that is laid up for those who fall asleep in godliness, it was a holy and pious thought. Therefore he made atonement for the dead, that they might be delivered from their sin.

John 5:24-29
Very truly, I tell you, anyone who hears my word and believes him who sent me has eternal life, and does not come under judgment, but has passed from death to life. “Very truly, I tell you, the hour is coming, and is now here, when the dead will hear the voice of the Son of God, and those who hear will live. For just as the Father has life in himself, so he has granted the Son also to have life in himself; and he has given him authority to execute judgment, because he is the Son of Man. Do not be astonished at this; for the hour is coming good, to the resurrection of life, and those who have done evil, to the resurrection of condemnation.

John 6:37-40
Everything that the Father gives me will come to me, and anyone who comes to me I will never drive away; for I have come down from heaven, not to do my own will, but the will of him who sent me. And this is the will of him who sent me, that I should lose nothing of all that he has given me, but raise it up on the last day. This is indeed the will of my Father, that all who see the Son and believe in him may have eternal life; and I will raise them up on the last day.”

John 11:21-27
Martha said to Jesus, “Lord, if you had been here, my brother would not have died. But even now I know that God will give you whatever you ask of him.” Jesus said to her, “Your brother will rise again.” Martha said to him, “I know that he will rise again in the resurrection on the last day.” Jesus said to her, “I am the resurrection and the life. Those who believe in me, even though they die, will live, and everyone who lives and believes in me will never die. Do you believe this?” She said to him, “Yes, Lord, I believe that you are the Messiah, the Son of God, the one coming into the world.”

John of Riga
Was not the repentance of St. Ephraim the Syrian sincere and deep? Even he, sensing that his end was near, besought his brethren, “O Brothers, accompany me into the world above with prayers, psalms, and offerings. Remember me on the fortieth day after my death; because prayers and offerings made by the living help the departed.”

St. John Chrysostom, Homilies on Phil 3:9-10
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.