There is no valid reason to believe that prayer to God yields results.

You have provided various stories in which people have prayed to God in times of need and gotten what they asked for. In your examples, it seems God's response to the prayers was always "yes." But it's also interesting that if prayer does work, and God listens, many times his answer seems to be "no." And so if one wishes to contend that despite this God does still listen, the answer as to why God said no is either that he has answered the prayer but in a way we don't understand, that sometimes the answer is no, or that God will ultimately answer the prayer but we have to wait for it. The following is a story/explanation I found that sums up the usual religious response to prayer's theological difficulties quite well - "There's a story of a man who was at his house when heavy rains poured down, the river crested, and the town flooded. As he stood on his front porch, the neighborhood completely under water, two men came by in a rowboat. "Can we take you to safety?" one called out. The man shook his head. "No, thank you. I have faith in the Lord and He will save me." A little later, the waters had risen and the man was on the roof of his porch when several folks happened along in a motorboat. "Say, there, would you like to come with us?" one of them called. "No, thank you," the man replied. "I have faith in the Lord, and He will save me." The waters continued to rise with alarming speed, and the man soon found himself on the roof of his house. A helicopter came by and hovered overhead as the pilot broadcasted, "Let me drop a line and get you out of there." "No, thank you," the man called back. "I have faith in the Lord, and He will save me." The man perished in the flood and went to Heaven, where he was met at the Pearly Gates by Saint Peter. Extremely saddened and upset, the man requested to talk to God. His request was granted. "Heavenly Father," the man cried, "I had faith in you to save me from the flood, and you didn't come through for me!" Astonished, God replied, "What are you talking about? I sent you two boats and a helicopter!" There's a lot of wisdom in that tale. Many folks are of the mind that if they want something, all they need do is pray for it. And that's ALL they do, just pray. They pray for a better job to come along. They pray for more money. They pray for a mate. Then they sit back, put their feet up, and do absolutely nothing. After all, God will provide for them if they pray hard enough and long enough. Now, I may be as far from a religious expert as you can get, but I don't think it works that way! Rewards come as a result of hard work, and of striving for a specific goal. Just the desire to succeed isn't enough, nor is dreaming. And nor is prayer alone. Prayer is supposed to be for guidance and a helping hand from God when the road gets rough or things don't look promising. It is not meant as a substitute for applying yourself. The Lord helps those who help themselves. I recently read that God provides food for every baby bird, but He doesn't toss it into the nest. How true these words are. The world is rich with everything your heart desires, and every resource you need to survive. But you have to go out and look for them yourself. If it's a better job or more money you want, you need to work towards it. If everything is handed to you, you truly will not appreciate what you have. Humans are funny that way. We take things that come too easily to us for granted. Daily, God gives us signs and shows us the way. The problem is, in this media-crazed society of ours, most of us don't notice the signs unless we're hit over the head with them. A sign is meaningless unless you know it's there. Guardian angels surround us at all times, helping to do God's work by indicating which path to take. You have to be aware of them, with your eyes and ears and heart. Sometimes the most obvious things aren't obvious." [1] Now, in this case, the answer was yes - God did answer the prayer but not in the way the man wanted/expected. A thinking person should realize that this can be said of absolutely anything, and not just God. This logic is presented wonderfully in the video "The best optical illusion in the world!" [2] Say hypothetically that someone decides to pray to a jug of milk for 1000 dollars. Like the case of praying to God, one of three things will happen. A check for 1000 dollars could arrive at your front door tomorrow – Look, an unexpected tax refund from the IRS! In this case, the jug of milk has answered your prayer, though in a mysterious way. Seven weeks later, you could get a raise in your job that gives you an extra 1000 per year – In this case, jug of milk has answered your prayer. All you had to do was be patient. Or, absolutely nothing happens. You would then ask me why, and I would tell you that we just have to trust the jug of milk. The jug of milk knows best. Will you get down on your knees and worship the jug of milk? You probably would not. Why? You probably would not because you know that the jug of milk didn't do anything. The jug of milk didn't cause you to get any money in the mail and it definitely didn't cause you to get a raise. You would know that the jug of milk did nothing, and that anything that did happen was a coincidence. Apply this logic to the extreme case of a cancer patient (not to get wrapped up in the "problem of evil") - The patient has terminal cancer. He prays to God and either - the patient makes a speedy recovery. God indirectly (as in he didn't come down from heaven and appear to him personally) answered the prayer. Or, the patient undergoes treatment for a long time and is eventually healed. God answered the prayer and all we had to do was wait. Or, the patient dies. In that case, God said no and because of our limited human understanding we just can't understand his answers to prayer, but we have to trust him that he knows best. Or apply it to one of your personal cases - take your grandfather's paycheck. He lost it, prayed to God and found it - God "answered" the prayer. But what if things had worked out differently? If he had eventually found it a while later, you would have said that God did answer the prayer too, and you just had to wait a little. And what if he had lost the paycheck, never to see it again? Would you conclude that therefore God doesn't listen to/answer prayers? No - you'd say that God is listening and you know with absolute certainty that he does but his answer was no and we're only human so we can't understand his reason for rejecting the prayer. You should understand that the VERY same results that God seemingly provides would be possible with the jug of milk. Or a tree stump. Or a football. Etc. And this applies for every single one of your examples where "God said yes" as well. So, as we have established, according to your view God sometimes says no to prayer. There is a very popular and strong question that can be raised against this view. Why won't God heal amputees? [3] This question is important, because it deals with the impossible - and it cannot be merely coincedental. When a person is diagnosed with terminal cancer, there is always a chance, no matter how slim it may be, that they will recover. When a person is born without a limb, there is a 0% chance that that limb will regenerate. What does God have against amputees? Theists say that sometimes God's answers to prayers is "no." For the amputee, for some reason, God's answer is always "no." There has not been a single recorded case of a regenerated limb. Why not? Does God not want to heal them? Simple logic proves that there is no valid reason to believe that God actually answers human prayer.