It all begins with a paradigm. With a worldview.
Things and events get interpreted as "facts" within paradigms. All "facts" are paradigm-laden. Which means there is no such thing as Cartesian objectivity (facts that are "clear and distinct").
A main reason for disagreement between an atheist and a Christian theist is: they have differing paradigms or worldviews. The basic issue then becomes: adjudication between competing worldviews. Why choose one worldview over the other worldview? Which worldview gives a truer understanding of experience and reality? Or, put another way, which worldview gives a more correct interpretation of things?
From a Christian paradigm (or any paradigm), natural disasters are interpreted in certain ways. The Christian paradigm begins with God. It is, according to a certain Christian worldview, rational to believe God exists, and that the attributes of God include "all-powerful," "all-loving," and "all-knowing."
Also - and this is very important - Christian theism holds that God has purposes for his creation that primarily have to do with him. God wants persons to love him and worship him. God wants persons to know him and be known by him. For all eternity. This present existence is seen as fleeting and hyper-miniscule in comparison to eternity with God. Because of the certain purposes of God, earthly suffering is viewed in certain ways. The purposes of any person's life do not necessarily include things such as "long life," "perfect physical and emotional health," and "personal wealth." (If you doubt that this represents Christianity, then I ask you to look at the physical sufferings of Jesus, the length of Jesus' life, Jesus' emotional agony in the garden, as well as the sufferings and distress of Paul and the apostles.)
Once a person accepts any worldview, then events and experiences get interpreted through the lens of that worldview. What, then, of the tsunami? To me, Christian theism says things like:
- Our entire world is subject to bondage and decay. We do not live in some naturally perfect world. The whole creation is fallen, and cries out for future redemption. So, we are not surprised by things like the tsunami.
- A life lived for 1 day is just as ephemeral as a life lived for 100 years when the denominator is eternity. How a life is lived is vastly more important than how long one lives on earth.
- The death of one person is as theologically significant as the death of 300,000 persons. Jesus wept at the death of one man Lazarus, and suffered and died on a cross so that all persons might live for eternity. How one person dies is theologically less significant than that persons die. Thus, we are saddened by the loss of any human life, and remain concerned about how each person lived their life while alive on earth.
- The loss of any human life is cause for weeping precisely because, on Christian theism, persons have been made in the image of God and have souls. Human life is thus especially precious and, literally, sacred. Thus we Christian theists are distinguished from philosophical materialists who hold that persons have no souls and are only animals. Grieving over the loss of any human life seems especially relevant on Christian theism. This is precisely because of the eternal worth of every human soul.