God wants us in a position of not understanding his full purpose in order to show our heart condition: proud and haughty, or humble?
If god invented natural evil in order to test whether people would submit to him regardless, then he is evil and unworthy of our worship.
Why does "God is love" have to be taken as a statement that God is composed entirely of love and all his actions are loving?
If all of god's actions are not loving, then god is sometimes guilty of unloving or evil actions and is not the god of christian theism.
I don't see how omnipotence automatically leads to being able to blame God for anything that goes wrong
I am not asking about "anything that goes wrong" but only about natural evil where human action and free will are not a factor. If you have absolute power over everything that happens then nothing occurs without your knowledge and permission. That makes god 100% responsible for the devastation of the tsunami. Morally his action and inaction are perfectly equivalent.
Let's try it with you: cofty , have you stopped beating your wife?
I have never struck my wife so I can reject your question. God did drown - or passively observed the drowning of - the tsunami victims, so his apologists can't reject mine.