"However, there is a notion that souls, even though they are purifed, will languish in Purgatory until they are brought to God's attention through prayer."
First, isn't God omniscient? Does He need anyone to "bring something to his attention"?
Second, say someone is in purgatory, and they have been fully "purified" through suffering. If no one is praying for them, will they continue to languish there? Will God allow them to continue to suffer, although completely purified? Doesn't sound like the righteous God I know. Then again, the God I know did all the suffering necessary, and now and forever considers me and all other true believers justified, purified, clean, and righteous.
Isn't that convienient, all you have to do is believe. What about the demons? They also believe in Jesus. Rmember what He did to them? The pigs, the cliff? How could he be so cruel to those who believe in him?
The Apostle Paul also appears to be praying for a dead person, Onesiphorous, in 2 Timothy 1:16-18
"For we must all appear before the judgement seat of Crist, so that each one may receive good or evil, according to what he has done in the body." 2cor 5:10
I hope you haven't forgotten these passages, as I know they are uncomfortable to preach on in a protestant congregation.
I don't know if arguss was being intentionally misleading, or he doesn't completely understand, or if I'm misunderstanding him, but that line about prayer calling God's attention to the soul in purgatory that has already been purged of his sin was incorrect.
You are not praying that they are somehow taken out of purgatory early like cookies being removed from the oven too soon, either. The soul will enter heaven when it is purged of the temporal punishment due to sin, and not before.
Our prayers for the souls in purgatory are "paying their debt", so to speak, and we join St. Paul- "Who now rejoice in my sufferings for you and fill up those things that are wanting in the sufferings of Christ, in my flesh, for his body, which is the Church." (Colossians 1:24).
Basically, we pray that God pours out the grace upon that soul which He earned on Calvary, but which was lacking in that individual due to his own sin, so that he may be brought to the state of perfection required to enter heaven.