The idea of "the power of prayer" is stupid on the face of it. First, you're presupposing a omnipotent diety that can and does directly effect the universe, changing the outcomes of events based on it's desires, whims, plans, whatever. And you think THAT diety is taking requests? When "God answered my prayers", you think that had you not requested it, it wouldn't have happened. You think that God answers to your puny human concerns? That shit is arrogant as hell.

But furthermore, it also flies in the face of two other common beliefs about God, at least in Christianity. "God gave man Free Will" and "It's All Part of God's Plan(tm)" (don't get me started on how those are already two mutually exclusive ideas and hundreds of millions of believers just ignore that cognitive dissonance). Many of the things that one prays for, like "getting that job", "winning that award", "ending the war", etc. directly involve altering the decisions and actions of others, which means that God would be stripping them of free will. Also, the most classic call to prayer is to heal the sick, or preserve one's life. But surely if God has a plan for everyone's life, at minimum everyone's birth and death must also be planned. How can he answer your prayer to save your life if it's his plan for you to die, yet still have an plan he's always been following? The irony is that people like to pull the "all part of God's plan" platitude particularly when someone has died before their time.

The one that really makes me annoyed, or even angry, is when something terrible happens, people are hurt or killed, and someone who was supposed to or had almost been there says something like "God was watching out for me". It's so self-centered and arrogant to attribute your simple dumb luck to God's will in that situation. Because, not only does it assume you are God's most special little guy that he's constantly paying attention to and protecting, but also that God willfully condemned those others who did fall to this terrible fate that he supposedly saved you from. It's all arrogance. I can't stand it.