Dr. Philip Ryken, Senior Minister of Philadelphia’s historic Tenth Presbyterian Church, offers a helpful theological analysis of how Christians should respond to Hurricane Katrina and the suffering left in the storm’s wake. The article offers wonderful pastoral advice on this question.
An excerpt: We respond with indignation, seeing that the poor have suffered even more than the rich. Hurricanes are indiscriminate in their destruction, raining destruction on everyone in their path. Almost no one on the Gulf Coast has gone unscathed.  But more of the poor were left behind, in many cases because they did not have a vehicle that could get them out of town, or the money to get a seat on a bus or an airplane.  The righteous see the structure of injustice behind the disproportionate suffering of the poor.    

We respond with trust, believing that God is working his purposes out for our nation and our world.  But this is not to say that we know what those purposes are.  Is Katrina God’s judgment on America, as some have said–his punishment for an unjust war on Iraq?  Or is it perhaps his wrath against the casino towns of Mississippi and the wanton depravity of New Orleans, as others are saying?  But if that is the reason for all this destruction, then what shall we say about all the other godless cities in this country, including our own?  And what shall we say about all the godly people whose lives have also been lost, and all the faithful churches that have been destroyed?  These questions are better left to God, who alone has the right to say what justice and what mercy he will show.