What a storm of fear and hope is in your cry! You see your brother lying as one already dead, and you cry out for his life, not merely of the body but of the soul. This is the proper anguish of love. Yet learn from this: the body lies paralyzed, but the soul still hears the voice of God. Never imagine that hearing is sufficient for salvation. Many hear the word ten times and remain insensible, but afterwards, a single blow of grace may fell the tree of hardness and cause it to bear fruit. Let your prayers be that blow. Persist without ceasing, for the Lord is not slow to answer but waits to display His mercy at the final hour, if only the heart turns.
You ask that he live until baptized and confirmed in salvation. A right desire, but beware of delaying upon baptism as though it were a charm. John baptized with water for repentance, yet the remission of sins belongs to the blood of Christ and the baptism in His name. If your brother has not yet received the washing of regeneration, cling to the hope that God can grant him the grace of true repentance even now, in the hidden chamber of his soul where no stroke can reach. For he that is dead to sin in his will is freed from it, though the body lie motionless. If he has ever in his life heard the word and stored some true knowledge, let that seed now spring up. The thief on the cross was saved in a moment, not by water but by faith confessed. So too, God may receive a soul that in its last breath turns from the deceitfulness of riches, the slavery of drink, and cries out to the Lord.
But take heed: do not pray against your enemies, not even against the illness itself as an enemy, but pray for his salvation above all. The world and its cares choke the word; your brother's coma may, in God's mercy, be the silence in which that word is heard at last. Lift up your heart with tears, yet with reverence, saying, "Lord, spare him not for the body's comfort, but for the soul's eternal healing. If he be not baptized with water, baptize him with Your Spirit and grant him the full confirmation of faith within." And if God should grant his recovery, let there be no delay: hasten him to the waters of regeneration, for after baptism we must remain ever dead to sin. If he then sin again, he mars the gift; yet even then there is the medicine of repentance, though not without wounds.
Therefore, do not despair. Continual remembrance of these things is itself a holy work. He that hath ears to hear, let him hear; and if your brother cannot now hear with the outer ear, the inner ear may yet open. I say this not willingly, but of necessity: I could wish no soul needed such late rescue, but the mercy that endures to the gates of hell is vast. Let your prayer be this: "O Lord, who didst send forth the word of the cross for the salvation of the world, let him not perish before that word reaches his innermost heart. Grant him, even in this sleep, the baptism of desire and the full remission of sins, through Jesus Christ our Lord. Amen."