There are other reasons to pray that have not been brought up.
One would pray to God for forgiveness. You could not become a christian without praying at least once. You need to confess you are a sinner and believe his son died for our sins and rose on the third day… This is done in a prayer.
One would pray to show thanks. If you believe that nothing can happen without God letting it, then any good things that happen to you is because God allowed them. So, we thank God for the good things in our lives.
To repent. How can you repent without praying.
For guidance. (yes, I know this will bring up other questions)
Originally posted by Opus1
However, I will defend the position that petitionary prayer is absurd if one accepts an omnipotent, omniscient deity. Calvinistic predestination has nothing to do with it. Any omnipotent, omniscient deity knows ahead of time (if God even exists within time) what will happen next minute, tomorrow, or 10 billion years from now. He knows perfectly well whether your sister will recover from her cancer well before you pray, before she gets cancer, or even before the universe was created. Of course, this gets into another problem with such theism, that of free will. The only real way out of this is to argue that God, in giving man free will, intentionally curtails his omnipotence/ omnipotence. This creates even more problems, such as whether a being could reinstitute omnipotence after losing it. And, in asserting this type of deity, we would be moving away from my definition of the god that most western theists believe in (and for whom I assert petitionary prayer is worthless), the omnimax variety.
I do not believe knowing ahead of time is an issue becuase I believe God does not exists within time. Its not will God know what happens in ten min or next week, because it just is to God. The knowledge is just there. Time has nothing to do with it.
Do we have free will. Yes
Does God ever intervene. Yes
Just because God if ever knowing does not mean he is always intervening.