We are having a lovely discussion in chat about the purpose and efficacy of prayer.
I am of the opinion that God has a plan and the future is completely set. However I also believe that you should pray for what you need and that God will answer your prayer.
What scripture forms the basis for our prayers and how do we rationalize praying when the outcome is set?
This is an awfully big question, but here are what I think are the key points from scripture:
Prayer is more than just asking for things. Tom Duckering's answer does a good job outlining this, but to gloss it again, prayer is communication with God which involves both talking to God and listening to him. As our primary form of communication with God, it reinforces in us our relationship with him in all its forms.
Prayer does include asking for specific outcomes. There are far too many examples to ignore: Abraham conversing with God over Sodom and Gomorrah, David pleading for Bathsheba's son, Hannah praying for a child, even Jesus praying that the cup be taken from him. God wants us to ask for things, even though he doesn't always give us what we ask for.
(Here's where it gets a bit controversial) God can and does "change his mind"†. My favorite example of this is Exodus 32, the story of the Golden Calf. Briefly, God tells Moses he is going to destroy the Israelites, but relents when Moses pleads with him not to. This is the classic definition of intercession: Moses stands between Israel and God and intervenes on their behalf.
This seems counter-intuitive, but God makes it quite clear that he wants people to intercede with him. See Ezekiel 22:30:
I looked for someone among them who would build up the wall and stand before me in the gap on behalf of the land so I would not have to destroy it, but I found no one. (Ezekiel 22:30 NIV)
This verse makes explicit what lots of stories in the Old Testament imply: God actively seeks people who will intercede with him. So in the story of Golden Calf, it seems quite likely that God went to Moses hoping that Moses would react the way that he did. Why? Because as long as Moses was faithful there was still hope for Israel, and the rest of the story bears this out as Moses goes down to the camp and restores order.
The important point here is that God does not change, we do. If Moses responds with apathy, then Israel is lost and the best that God can do is show his righteous wrath by destroying them. But because Moses responds with prayer, God can take the better path of using Moses to lead them back to him.
What about times when we intercede but we have no actual control over the situation, like praying for healing? Our prayers affect what God does because our involvement changes the picture from God's perspective. If we are indifferent and don't bother praying, then what he does will not have any great effect on us. But if we are deeply involved in prayer, then our hearts are on the line. If God comes through, we will be affected and we will give the glory to God. Our prayers, then, factor into God's decision of what he will do, and maybe, just maybe, our involvement will be enough to tip the balance.
If none of this made any sense, here's at least a great C. S. Lewis quote on the topic:
"Praying for particular things," said I, "always seems to me like advising God how to run the world. Wouldn't it be wiser to assume that He knows best?"
"On the same principle", said he, "I suppose you never ask a man next to you to pass the salt, because God knows best whether you ought to have salt or not. And I suppose you never take an umbrella, because God knows whether you ought to be wet or dry."
"That's quite different," I protested.
"I don't see why," said he. "The odd thing is that He should let us influence the course of events at all. But since he lets us do it in one way I don't see why He shouldn't let us do it in the other."
(C. S. Lewis, God in the Dock)
† God "changes his mind" perhaps only from our perspective inside of time. God actually seems to exist outside of time entirely, and so perceives all points in time simultaneously. It's hard to understand this without time words, but before (a time word!) the creation of the world God sees everything that will happen, and writes his entire plan around what he knows that we will do.
Prayer is not primarily/just a means of asking God for stuff. In Matthew 6:9-13 Jesus does a brilliant job of correcting our ideas on prayer when he teaches the disciples (and us!) "The Lord's Prayer". Jesus after all is the perfect teacher here. He is God and Man and knows what pleases his Father but knows our human situation too.
The focus of the prayer is on God and not us - especially in the first half. Then the second half we express our relationship with God.
Starting with "Our Father in Heaven" we're expressing that God is our Father (thanks to Jesus!) but that he is also heavenly (i.e. holy, holy, holy).
We pray that His name (character) is hallowed (honoured as holy) and we express a desire to see His kingdom come.
It teaches us to pray things like "Your will be done" rather than "God, please do my will".
We pray that God will provide what we need and that we are constantly reminded of our dependence on him when we say "Give us today our daily bread". And so on.
I can recommend this book on the Lord's Prayer which I read recently: Our Father (Enjoying God in Prayer) by Richard Coekin
In terms of rationalising prayers in the light of predestination, I think Luke 11:11-13 is helpful. It compares God to a good earthly Father who when asked by his children will not given them bad things. I think the parental comparison is good. Parents know that their children need things (i.e. they buy food in advance) and will give thing to them but it's so much better when a child humbly asks and thanks their parents.
Prayer is communication to God, whereas reading His recorded Word (the Bible) is how He [most typically] communicates to us.
To quote Paul, we are to be "praying at all times in the Spirit, with all prayer and supplication. To that end keep alert with all perseverance, making supplication for all the saints". As Christians in the world, we are engaged in a constant battle against evil. We are fighting daily to hold territory claimed for Christ, and to push a little further into Satan's strongholds.
If we are not mimicking Jesus' life and examples of times in prayer to the Father (sometimes he would spend entire nights in prayer - and I can't see that being idle chitchat), I would say we have to ask ourselves if we're really being the "little christs" (Christians) that we claim to be.
A few years ago I did a short personal study on prayer, and published my study on my blog, from where I drew this answer
We know that God listens to and answers our prayers:
Matthew 7:7: "Ask and it will be given to you; seek and you will find; knock and the door will be opened to you."
John 14:13: "And whatever you ask in my name, I will do it, so that the Father may be glorified in the Son."
Psalm 116:1: "I love the LORD because he hears and answers my prayers."
Matthew 6:8: "Do not be like them, for your Father knows what you need before you ask him."
(Those are just a few verses that come up when searching Google for "god listens to our prayers bible verses".)
We rationalize praying when the outcome is set because praying is not just about outcomes. Prayer brings us closer to God.
For example, we can pray for understanding and mercy. God's answer to that prayer could be gaining a better understanding of God's will in the situation and granting us peace.
As others have pointed out, there are many places in the Bible where believers are encouraged or even commanded to pray. So from a Biblical point of view, the question is not, "Should we pray?" It is fair to ask, "Why should we pray?" or "What is the effect of our prayers?"
Luke 18:1-7 (NKJV): Then He spoke a parable to them, that men always ought to pray and not lose heart, saying: “There was in a certain city a judge who did not fear God nor regard man. Now there was a widow in that city; and she came to him, saying, ‘Get justice for me from my adversary.’ And he would not for a while; but afterward he said within himself, ‘Though I do not fear God nor regard man, yet because this widow troubles me I will avenge her, lest by her continual coming she weary me.’” Then the Lord said, “Hear what the unjust judge said. And shall God not avenge His own elect who cry out day and night to Him, though He bears long with them?
God wants to do good things for his children. You could say that he already knows what we want and need and so there is no point in telling him. But then we get into logical conundrums. You could say that God is all-knowing and so he knows what you would have asked for if you had asked. But then you're saying, not that God knows everything that happened, but that he knows something that might have happened except for the fact that it didn't happen. If we never vocalize what we want, have we even thought through in our own minds what we want?
I -- like, I am sure, many other Christians -- am confused by John 14:13, "And whatever you ask in My name, that I will do." It certainly SOUNDS like it means that God will give us anything we ask for. But we all know from personal experience that that isn't true. Far more people have prayed to win the lottery than have won the lottery, etc. Lest someone say that that's because we're deluding ourselves in thinking that we are among the saved, surely we would all agree that Paul was saved, and yet Paul said, 2 Corinthians 12:8-9 " Concerning this thing I pleaded with the Lord three times that it might depart from me. And He said to me, “My grace is sufficient for you ..." In context, Paul had some sort of medical problem -- scholars debate just what it was, but it doesn't matter for this point -- he prayed three times that God would heal him, and ... God didn't heal him. So God did NOT give even the faithful Apostle Paul everything he asked for.
(And lest an atheist say, "Aha! Another false statement in the Bible!", surely everyone who read the Gospels when they were first written knew that Christians don't get everything they pray for. If the Bible was really written by people trying to pull off a huge hoax, why would they deliberately include a statement that said something that everyone who read it would instantly know was not true? If I was writing a book trying to convince people that I had been kidnapped by aliens, surely I would say that this happened in an isolated place far from civilization in the middle of the night, so no one could prove me wrong. I wouldn't say it happened on the 50-yard line during halftime at the Superbowl.)
So bringing those two points together: If God is all-knowing and all-wise, than he presumably could form a perfect plan. But if one of his goals is to make his children happy, then it follows that his plan must take into account the wishes of his children. Of course God is all-knowing and we are not, so sometimes our wishes are, in fact, bad for us. A wise and loving God won't give us things that he knows will hurt us. But given many possible good things, he can give us the thing that we want. It's like parents giving birthday presents to their children. If a 6 year old says, "I want a machine gun for my birthday", a wise parent is not going to give it to him just because he asked for it. But if the parent is deciding whether to give the child a baseball or a toy train, what the child wants would likely be a major deciding factor.
To take the silly extreme, if you pray, "God please help me to kill my neighbor because he annoys me with his loud music", I doubt that God will grant that prayer. But if you pray, "Help me to get a job as an accountant" versus "... as an auto mechanic", he might well honor that, as the difference may well be purely a matter of what you enjoy. Then again there may be larger implications that you don't know about. I've had a few times in my life that I've prayed for something, it didn't happen, and I've been frustrated and disappointed, and then sometime later I saw that if I had gotten what I'd asked for, it would have been bad for me. I'm sure there have been other times when I've never realized why it would have been bad.
