You know, this has been an issue for me lately. God says, 'ask you and shall receive' but taken literally (without qualifiers) that is blatantly untrue. I've asked for a lot of things that did not happen and they weren't sinful or bad things either. I can clearly see in my own life that God has His own agenda that has nothing to do with what I want and may ask for, and He tends to bulldoze me into what He wants regardless of my personal dreams and desires.
On the other hand, if we are only meant to be asking for certain things (where the 'qualifiers' come in), how are we supposed to know what those things are? And if they are things God desires for us to want rather than things we actually do desire for ourselves, why would we be asking for them anyway? It all seems paradoxical to me.
Since considering and responding to her comment has rewardingly occupied much of my mind and heart this morning, I'm sharing my response here. It's a question that applies to each of us, I think, when we're honest:
This all makes sense to me, and it's big enough to be dangerous to address in only the blanket, general terms I can in this forum. In things like this, the devil's (sometimes literally) in the details of our lives, so I won't pretend that my remarks actually address your personal situation.
That said, the exegetical principle of Scripture interpreting Scripture seems wise to apply here. "Ask and you shall receive" and its corollaries are perhaps best understood in accord/tension with the command to "Seek first the Kingdom of God." The most powerful prayers in my life are those that center on His promises and desires for the advance of His Kingdom in my life, in my church, in my city. They aren't impersonal by any means, and I try to steer clear of the vague generalities and wishy-washiness of "if it be Thy will" (it's a good principle, but too often used as an escape hatch to cover our disappointment if something doesn't happen, as well as to avoid the genuine work of being engaged with seeking His will).
So how are we to know for what we ought ask? For me, it's about the Kingdom, about letting the seeking of it transform my desires. If prayer isn't in some part changing me, I question its effectiveness. Seeking first the Kingdom, we're told other things will be added to us. That's a clear order of operations, and while it by no means precludes asking what we need or wish, what we need or wish should be changed (both all at once and bit by bit) by the gospel.
God does have His own agenda, without a doubt. That was the bread Jesus ate—to do the work and will of the Father who sent Him. That fully outshined, overshadowed, and transformed His personal dreams and desires (He struggled with the Cross until the end, but did not sin). Do we want to relate to the Father as He did? In our flesh, that's still a struggle.
There's a cross, a daily one, for each of us. Desire isn't set aside (that's more Buddhism's province), but in many respects it is put to death and resurrected—redeemed. We aren't any less ourselves for this, but it's both frightening and frustrating to give it up. We each still carry the desire to be kings and queens of our own small worlds—little gods—whether born of fear or pride (and of course, it's almost always both). The rebellion still smolders within, but so does the hope of glory.
We can only be the kings and queens we are intended to be under the Sovereign, and by grace we often won't be allowed to build any separate empires. Thank God—I don't want to move into a castle that's only going to be destroyed when He Himself is preparing a greater one for me.