This seems like a very simple passage to understand, but once you probe just a little you’ll find that it’s one of the most profound you’ll ever read. It’s been misused quite a bit by some televangelists, so let’s clear up some common confusion about it.
First off, is this a blanket promise that he’ll give us whatever we ask for? Some preachers might teach so, but I don’t agree. Read the latter portion of the passage, and ask yourself some common-sense questions. Jesus compared our heavenly Father to a human parent, arguing from the lesser to the greater. If a human parent gave his young child everything he asked for, would that be showing real love? Of course not. Quite frankly, I'd rank it as child-abuse almost on the level of hitting them. We desire things all the time which are harmful to us and others, so our Father lovingly and wisely tells us “no.”
So what is Jesus talking about? What’s his point? He wants to encourage us to be bold in our prayers, always acknowledging that our Father knows infinitely better than we do, and will answer according to his perfect plan which will glorify himself and benefit us. If we found out about a parent who neglected his children, who failed to provide them with food, clothing, or shelter, what would we think of them? Or even worse, if the child, asking for a piece of bread, instead got something useless or even harmful? So if a human parent (and the best of them aren't sinless) wouldn’t do that to his own child, how much more can we trust our Father to provide what we need!
By the way, I’ve also used this as a witnessing passage. I’ve talked to lost people about the claims of Christ, and they expressed doubt in the truthfulness of the Good News. I've pointed them towards the promises of vss. 7-8 and challenged them: “Just pray to him, saying ‘If you’re there, Jesus, if this is true, show yourself to me. Make it clear to me.’ If the Bible’s a bunch of myths, then you’ve got nothing to worry about. But if it is true, then I believe that Jesus will keep this promise and make it clear to you.”
Do some preachers misuse this passage? Absolutely. But in reacting to them let’s not overreact in the opposite direction. We need to be bold in our petitions to him, not timid! We don’t want to presume on him, but we need to realize that he is perfectly capable of going beyond what we ask or even imagine. Are you bringing “God-size” prayers before your Father? Why not?
Thou are coming to a King,
Large petitions with thee bring;
For his grace and power are such,
None can ever ask too much.
Father, you're so big, and my prayers are so small sometimes. Help me to pray under the guidance of your Spirit, and know that I’m praying to Almighty God.