I avoid referring to it as a problem of evil, because the problem of evil is an old stereotypical question with lots of canned answers. It's phrased in a way that makes it easy to wave the question away with some kind of an unfalsifiable hypothetical like "free will" or "the greater good".
The problem I see with it is that Epicurus
raises the question formally, referring to God in third person, appealing to logic first and foremost, and using the cover-all term for evil instead of using one particular example that is far easier to imagine.
But if you put the other person into God's shoes, maybe add some graphic details to make them
feel the vileness of the situation, and have them answer a question as if
they were the one who allowed evil to thrive? Now
that's when you get some out-of-the-box thinking.
"I don't want to violate the pedophile's freedom to rape" sounds far more confusing than "Everyone deserves free will, whether they use it for good or evil", does it?
And if you only get more confused by your own answer, that usually means the answer is bad, even if it is technically unfalsifiable.
If there's anything I learned watching the best teachers in my university, it's that phrasing the question in a thought-provoking manner prevents one from automatically settling for the first answer they can find. Dunno, maybe that kind of thinking is too primitive and informal for actual philosophers. But I'm not trying to pass for one, anyway.
The traditional answer, so far as I am aware, is that the infallible entity is both so pure and so above mortal bonds that it is beyond our ability to comprehend.
Note the words "infallible" and "pure". These terms are absolute and general; in other words, they have no solid meaning. If someone used such meaningless terms in a physics paper, they wouldn't be taken seriously.
Allow me to explain why I dislike them.
When I say "apple", you imagine an apple's texture, color, and taste. You know when to call it an apple, and you know someone's full of shit when they point at a strawberry and tell you "this is an apple".
But when I say "infallible", do you picture what an infallible entity could be? What it would do in this or that situation? How do we know if some hypothetical person is truly
infallible or just a guy who hasn't made an error
yet?
The answer is: we don't, because the term "infallible", while it has some formal definition, is devoid of
actual meaning that your brain can parse like it parses the concepts of apples and strawberries and even quarks. Therefore, when you hear someone use it in a serious discussion, that's is a good indicator that someone didn't think their words through.
And there are more problems with those terms. Let's use 'pure' for an example. Let's pretend that 'purity' can be absolute, whatever that means. But what is the deity is pure of? Is it pure of a thirst for justice? Is it pure of empathy and kindness? Because then the answer makes sense, but not the way theists meant it to.
But let's ignore the terms and look at the entire answer.
So, let's pretend for a moment the answer is
true. Everyone's going to live forever under the heel of a creature so alien that our ant-like little minds will never comprehend why it's allowing absolutely atrocious things to happen to us.
That raises a new question: if the deity is so incomprehensible and malicious by
our standards, isn't it going to
keep being incomprehensible and permitting malice in its domain
after everyone's dead?
And if, as some theologists claim, after death we change into something so alien that we'll be able to comprehend the deity and enjoy watching evil happen the way it does, then why do they think our existence will continue? We'll be completely changed, at least on an emotional level.
As we can see, that answer only makes one's belief system
more confusing in the end. Hence, there's something wrong, either with it, or with one's beliefs.
As such, God's morality cannot be questioned not so much because we are not allowed to question it (although that's definitely a factor!), but more because we cannot pose meaningful questions about it.
Ah, the eternal answer: "Don't ask stupid questions, just believe me on my word."
Saying "you can't question X" is functionally the same as saying "all of my answers make no sense so I'll just pretend that the question doesn't exist".
Of course, it sounds kinda deep when you dress it up in meaningless but absolute terms, but is there a good
reason to believe that you can't question something? Or do you believe it because none of the pleasant answers make sense, and you don't want to accept the unpleasant ones?