I'll try to make the same point in a brief manner:
1) Mainline Christians say God controls the whole world
2) Mainline Christians say the existence of evil is the result of free will, and that explains how the harm from evil can exist in our world
3) But the Tsunami was not the result of human free will
4) And the Bible says nothing about Tsunamis having free will--in fact, natural disasters are often described as acts of God
5) so any natural disasters at least have God's permission, if they weren't caused by Him outright
6) so God gave permission for the Tsunami to slaughter a quarter-million human beings
7) a loving God would not slaughter so many human beings
therefore
Conclusion: there is no loving God.
Explain which of the premises 1-7 you disagree with.
This answer might not satisfy you, but it comes down to the fact that for Christians, many things are taken on faith.
1. I do not know of a mainline Christian denomination that teaches that God actively "controls" every event on the Earth.
2. In Christian Ethics, there is a difference between objectively undesirable events in the natural world, and the subjective "evil" of human action.
3. No one has said that it was, the point is moot.
4. I believe you are using insurance company terminology, not quoting the Bible.
5. God does not "permit" what exists, He is the cause of it coming into existence.
6&7. Are a straw men based on moot or spurious points in you line of reasoning. If the premise is flawed, so then the conclusion.
I offer as evidence for the existence of God the reaction of the sentient human race to the plight of those hurt by this disaster. In a world devoid of God and good, this would be an empty waste of resources.