A lot of this thread has moved away from anything that is really meaningful or appropriate for game purposes. I have answers to many of the questions raised which satisfy me--but I do not wish to derail a meaningful discussion about in-game prayer with real-world theological issues. Anyone who wants to address any of these questions can start another thread.
As to "repetitive prayers", these are not without value. I come from a strongly non-liturgical tradition, and always looked askance at liturgy, particularly as it was used in "high church" settings. The problem I perceived was that people (like my aforementioned friend) could rattle off prayers without giving any thought to what they were saying. Thus in some of my time spent in "mid church" settings, whenever I had a hand in designing worship services, I made a point of bringing in meaningful statements within the liturgy that would not be familiar, so that participants would have to pay attention to what they were saying.
Then I read an essay by C. S. Lewis that was completely counterintuitive to me. He asserted that it was important for the liturgy used in public worship to be uniform and familiar, to the point that you could recite it without thought. He did not wish to be thinking about whatever it was he was going to say next, or whatever it was he just said; he wanted to be thinking about the person to whom he was saying these things. That was what mattered in worship, he suggested, that we have our minds on God, and not on what we are saying and doing. Thus the less we have to think about the motions, the more we can focus on the divine.
I am still "low church" in that regard; but I understand "high church" a lot better. I also understand repetitive prayers--the use of liturgy in that way is akin to singing songs you know so well that you have your mind elsewhere while singing them, akin to the use of "tongues" to worship God, all three ways for the person to have his mind on God while his mouth is worshipping without requiring his attention.
There is a lesson of importunity in scripture. Jesus says seek, ask, knock--but the tense there is linear, keep on seeking, keep on asking, keep on knocking.
I think, too, there is a difference between praying without ceasing and simply believing that God will take care of everything. Paul's admonition suggests a conscious awareness of the presence of God, even if it does not require a constant verbalization.
That, though, is not something that can easily be put in game terms. Either people are praying constantly or they are not; but when they wish to petition for specific results, they must do so specifically. As referee, I am not going to ask whether your character has been constantly focusing his mind on his deity and the blessings that flow therefrom; if I did, I would expect that the clever player would always say yes, and how could I challenge this assertion? Lauren Hastings pours of scripture, meditates on what she has memorized, uses it--as Eric observed, she continues to use what worked for her, and had no reason to change it. (I will note that through her influence her priest friend began using the liturgy in the same way, reciting the prayer for eternal rest against the undead and the ceremony of anointing with oil for the healing of the wounded. Even within the technique, there is some variety.) Lauren also prays, here and there, conversationally, looking for insight from God without actually asking for something specific, as part of her thought processes.
Lauren's spells, though, are less like prayer in most cases, and more like "standing on the promises", expecting God to do what she believes He said He would do. In this, they stretch the sense of "holy magic" a bit, as she does not think of them so much as prayers but as exercises of her faith.
--M. J. Young