NOTES for Mar 11:24
Here is a remarkable example of what can result from pulling quotations, even from the Gospel, even from the words of Christ, out of the context in which they stand. People who read this verse almost inevitably ask again in distrust: "How is that? And if I ask, believing that I will receive, say, for the death of my enemy? Will that also happen?"
But Christ here is not saying what one may ask for and what one may not; He is speaking of how to ask. He is speaking of the power of faith in prayer, not of what prayer should be directed toward. That is also addressed, but in another place; see Matt. 7:11; Luke 11:13. We read as though we wanted not to understand Christ, but to catch Him in His words. And He is trying to teach us trust, the ability to live not by what has already happened, but by what is happening right now, at this very moment of our communion with God.