For the Calvinist however, prayer is a meaningless ritual since they hold that God has decided everything and hasn't considered prayer occurring in time.
Does this include Judas? Christ prayed that God would protect Peter from Satan. One can only conclude our Lord did not pray the same prayer for Judas. It is clear that God chooses some and to others He passes over. That is a fact taught in scripture as early as Moses and the Angel of Death. One could even go back to Cain and Abel.
For the Calvinist however, prayer is a meaningless ritual since they hold that God has decided everything
Prayer is the way we know the will of God. Yes, God has decided everything for that is the definition of sovereignty and that is the way we are submissive to God's calling, not our will but His. But I wouldn't be so bold as to make the claim that my prayers are righteous and holy to the will of God. All of our prayers are so poor to God that the Holy Spirit must intercede for us.