Why do Orthodox Christians pray for the departed?
Out of love for them! Orthodox believe from the teaching of Sacred Scripture that we are obliged to pray to God for the departed, to offer the Holy Eucharist for them in remembrance and to give alms in their behalf, since they cannot do this for themselves. We leave the results – or even whether there is efficacy in prayer for the departed, since we cannot know for certain – up to God and His mercy. Blessed Theophylact speaks about this: “For the sinners who die are not cast into hell (until the Final Judgment); but it rests in the power of God such that he may even pardon them. But I say this because of the sacrifices and almsgivings made for the sake of the dead, which works are of no small benefit even for those who have died in grave sins. It is not so certain, therefore, that God sends to hell one who has killed, but rather that he does have the power to send him.