Compare the argument from Pseudo-Empiricus:
If God is willing but not able to get rid of evil, how is he all-powerful?
If not willing but able, how is he good?
If willing and able, why is there evil?
And a parallel argument from someone halfway through watching A New Hope:
If George Lucas is willing but not able to avenge the destruction of Alderaan, how is he the script writer?
If he is not willing but able, how is this movie not utterly nihilist?
If he is willing and able, why is it not avenged?