If Matthew 21:22 isn't true then what is the point of prayer? Wouldn't prayer be nothing more than a waste of precious time?

God is not a vending machine.

Too many people try to understand the Bible by dissecting a verse or a paragraph.

Bad analogy alert
It's like trying to say you know and understand stew because you picked out a piece of celery and ate that.

Admittedly I have no idea for what you are praying. If you believe without doubt and pray for another man's wife..., should God grant the prayer? If your mother is dying a slow miserable death and praying for release, and you are praying for her recovery; whose prayer should God grant?

It sounds like a deflection, I'm sorry but if you aren't receiving what you pray for, there is a flaw within the nature of the prayer, or God will deliver, but what God delivers may not look like what you thought you were asking for, and God delivers on his schedule, not yours.

I think SGT Steve McFarland nailed it. Too often prayer is entered into as a negotiation. If God will ______, then you will _______. Think about it. Do you give your children what ever they ask for, whenever they ask for it? Do they always (or for that matter ever) understand why you may deny them something they desperately want?

You aren't taking the full context of Matthew 21 into consideration or the larger lesson which is the power of not only prayer but belief. This is much more than the 1 dimensional interpretation you gave. You aren't rubbing a lamp and making a wish. This is about faith, conviction and belief equipping followers/believers. If you don't like the Bible in general, religion as a whole or maybe you have a gripe about Christianity that is fine. That is your right to have that opinion. I will counter that if you are going to criticize the scripture don't cherry pick a single strand and use that one piece as the base of your argument. Prayer is much more than ordering what you want. It's a conversation based on belief.