Many people believe that prayer is unnecessary, because if God wants something done, He will do it whether we pray or not, and if something is not His will, it will not happen, even if we pray for it.
No one refutes this idea better than C. S. Lewis. He has written about prayer in numerous places. Three of his best works on prayer are “Work and Prayer” in God in the Dock, “The Efficacy of Prayer” in The World’s Last Night, and what he writes about prayer in his Letters to Malcolm.
Essentially, the argument of C. S. Lewis is this: Any responsibility in this world which God can pass on to human beings, He does pass on to human beings.
God prefers not to do something if a human can do it.
And God has provided two means by which we can accomplish these God-given tasks: work and prayer. And just as we view work as a way of getting things done in the world, we must begin to view prayer similarly.
Here is what Lewis writes in “Work and Prayer”:
You cannot be sure of a good harvest whatever you do to a field. But you can be sure that if you pull up one weed that one weed will no longer be there. You can be sure that if you drink more than a certain amount of alcohol you will ruin your health or that if you go on for a few centuries more wasting the resources of the planet on wars and luxuries you will shorten the life of the whole human race. The kind of causality we exercise by work is, so to speak, divinely guaranteed, and therefore ruthless. By it we are free to do ourselves as much harm as we please. But the kind which we exercise by prayer is not like that; God has left Himself discretionary power. Had He not done so, prayer would be an activity too dangerous for man and should have the horrible state of things envisaged by Juvenal: “Enormous prayers which Heaven in anger grants.”
Prayers are not always – in the crude, factual sense of the word – “granted”. This is not because prayer is a weaker kind of causality, but because it is a stronger kind. When it “works” at all it works unlimited by space and time. That is why God has retained a discretionary power of granting or refusing it; except on that condition prayer would destroy us.