Good Christians only may answer...

[robvalue]

Of course we have the whole problem of god's plan versus the supposed agency of humans (we'll leave our other animals for simplicity).

Do we have the power to cause events to change from god's plan? Again, each answer is problematic.

If we don't, then we're just part of a theatre. We're not having any effect at all that wasn't scripted for us. If we do, then God has no plan after all, at best he can guess at what is going to happen; or else he constantly screws with things to negate any change we're actually making, although even that is a stretch as an explanation.

Anyhow, if we do have the power to change his plans, I suppose prayer could be asking him to screw with other people so that they do stuff to make whatever you want happen. That only works for prayers that can be accomplished this way though. It's not going to stop any hurricanes.