You wrote -
"Actually we can't change God's will and the purpose of prayer is communication with God, sort of like when we talk to our friends. Sometimes our friends do favors for us when we ask them if it seems okay with them and sometimes they don't. God's the same way."
We are not getting anywhere with this. I still contend that if God has a plan and "it" intends to stick to the plan without letting humans in on it, then there is no point to prayer other than the "feel good" scenario. To my understanding communication is a two way street. Converseing with God is a matter of subjective opinion. You have to interpret whether God is talking to you based on things happening around you. Example - Lets say that I pray to God that "it" keeps myself and my family safe on a cross country trip. Halfway through the trip a truck pulls out in front of me and I jerk the wheel and miss the truck, while spinning out into a ditch. I am safe!! Did God protect me because of my prayer or was it part of Gods will that I live. If we all were killed, would it be Gods will or would it be that I didn't pray hard enough. I could "logically" assume that because I prayed I was saved from death. But it could have just been my eyes processing the outside situation, relaying informaton to my hands, and then my hands quickly jerking the wheel with a sharp reflex. Either way I don't think their is evidence to support the validity of prayer.
You wrote -
"God is disappointed when things don't work out."
I am not sure if God feels disappointment or not. It sounds like a human emotion. If I were to apply a human quality to God I would rather use one like 'Indifference'.
You wrote -
"Well, it's because God gave humans the capacity of free will and sad to say, many humans use it to do bad things."
This one has always bothered me. How can God have a plan for humanity, but give him free will. They don't fit together. It seems the free will of humanity would disrupt the plan of God. I know that I could be missing the "bigger" picture, but small things forever change the complexity of the larger happenings. If God knows our behavior before we do it then he isn't really looking out for us - is he?
I believe in the idea free will, because I believe we behave according to the conditions we are under. Religion is a man-made construct. God might be the same thing. I don't believe in a plan, nor do I believe God listens to prayer. God is more than likely not a saintly old man in the clouds granting life or death based upon who asks and who doesn't. That is absurd!!