New Thoughts
This last sentence above seems to sum up the situation so well. There are three stages of intercession. The first is the prayer for one who has not yet received Christ as Savior. In this case, humble asking for such a one to find faith to believe, and thereby attain to life, is the appropriate course. This is aiteo, asking favor of a superior. The second stage is intercession for the believer who has slipped into sin. Such a one is still a believer - has not blasphemed the Spirit and thus gone beyond redemption. As such, we are told we are in a position to pray confidently, as to an equal - a friend (erotao). In this case, our answer is assured by promise, and our faith can be confident in the outcome. The final stage is that of the once-believer who has reversed course, and rejected the Gospel he once grasped. Such a one in has in effect blasphemed the Holy Spirit, and gone beyond redemption. No longer can we offer the confident prayer of the second stage, and there seems a question as to whether even the humble prayer of the first stage is appropriate. I tend to think it is, for only God can know the full extent of another's fall, whether it be truly beyond redemption or not. If, as with the prophets, we are specifically told for a specific case to cease our prayers, then clearly we cease our prayers. I think that in all other cases, we return to the humble prayer we would have had for them were they never believers, a prayer that God might see fit to bring them back to their senses. This seems to accord well with the prodigal son.