At the Funeral Mass of his father, Antonin Scalia, Fr. Paul Scalia included an explanation on why we should pray for those who have died. The following is taken from the homily he delivered on February 20, 2016:
We look to Jesus, today, in petition---to the present moment here and now, as we mourn the one, we love and admire, the one whose absence pains us. Today, we pray for him. We pray for the repose of his soul. We thank God for his goodness to Dad, as is right and just. But we also know that, although Dad believed, he did so imperfectly, like the rest of us. He tried to love God and neighbor, but like the rest of us, did so imperfectly. He was a practicing Catholic—practicing in the sense that he hadn’t perfected it yet. Or, rather, that Christ was not yet perfected in him. And only those in whom Christ is brought to perfection can enter heaven. We are here then, to lend our prayers to that perfecting, to that final work of God’s grace, in freeing Dad from every encumbrance of sin.