There is no rational, demonstrable, or defensible reason for a compassionate God to allow any of that. The excuses you will hear for it are either illogical, contradict known facts, or require wildly implausible assumptions for which there is no evidence.
Why would a god allow such suffering in this world? Why are there people with crippling, painful disorders and diseases?
The Atheist Perspective
Why do bad things happen to good people?
Answers: Atheist, Christian, Muslim, Hindu
Can god make a rock so big he can't lift it?
Answers: Muslim, Atheist, Christian
If our choices are predetermined, how are they real choices? And how are we accountable?
Was it okay for Hitler to kill the Jews? If not, why not?
If God created everything and decided how it would be, wouldn't our sins be his fault?
Answers: Atheist, Christian
Atheist Proving History: Bayes's Theorem and the Quest for the Historical Jesus Richard Carrier Atheist Atheism: A Philosophical Justification Michael Martin Atheist The End of Faith: Religion, Terror, and the Future of Reason Sam Harris Atheist Not the Impossible Faith Richard Carrier Atheist Hitler Homer Bible Christ: The Historical Papers of Richard Carrier 1995-2013 Richard Carrier Atheist God Is Not Great: How Religion Poisons Everything Christopher Hitchens Atheist Humanism: A Very Short Introduction Stephen Law Atheist The God Delusion Richard Dawkins