In answer to a Slate Explainer column, I noted:
For one, Catholics, who unlike Protestants believe in purgatory, think prayer helps speed the transition from limbo to heaven.
Why is this different from helping people go into heaven itself? That is, under the logic of the belief structure? From personal experience, I also wonder how many Catholics truly believe in purgatory or limbo these days.
Under that logic, when a Christian prays for someone who has died, he is also praying for himself. He therefore brings himself closer to God and closer to salvation.
This seems the most logical path. For instance, a prayer of thanksgiving recognizes one's blessings and helps one remain humble about them. A prayer in honor of someone who died, including to obtain solace and strength, also is personal and humble. Like chanting, yoga, mediation and other devices, prayer also is a means to center onself and reach what many see as "sacred," a special place that often but need not solely be in some fashion ultimately about a God-type being. It also might be a means to be right with nature. This makes it a type of "religious" experience in my eyes.
Prayer is personal as well as having a communal aspect. A group of people praying can be like any other group -- each person on their own is one thing, as a group, there is a certain power. It also can be important to know people are praying for you. Maybe, this even works while in limbo? Anyway, just like someone appreciates when they know a person is thinking about them, knowing a person is praying for you can help. To the degree that well being is in part mental, this also might have some value when you are sick. Someone alone, for instance, might have a harder time of it even if they have the same disease, the same medical resources.
Of course, some faiths -- especially in mythology -- believe that supernatural beings are listening, and do care if many people are appealing to them through prayer.
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* The photo has the woman appearing to hold a rosary. Such items can serve as a means of focusing yourself. It is something like the idols of the old, sometimes ridiculed as if people were praying to stones. But, many didn't think the idols were gods themselves, but means to focus oneself to a supernatural that humans could not themselves see.