I’m not religious, so that might be why I don’t understand the so-called ‘problem of evil’. To me, it’s a sophomoric question: If God exists—and is all-good, all-loving, and created everything—, then explain how evil came to be and why it seems to be so prevalent. There’s no reason to accept Occam’s Razor, but this might be a good time to adopt it. A narrative of God is created, and then—as with retrograde planetary motion to justify a geocentric ‘solar’ system—one needs to create odd sub-narratives to fill holes in the main storyline.
The problem of evil is that it doesn’t exist. Evil doesn’t exist. Denotatively, it can be defined as very bad. Connotatively, a moral element is manifest in the term, but the word is unnecessary judgmental hyperbole.
Etymologically, the word evil derives from the
Old English yfel (Kentish evel) "bad, vicious, ill, wicked," from Proto- Germanic *ubilaz (source also of Old Saxon ubil, Old Frisian and Middle Dutch evel, Dutch euvel, Old High German ubil, German übel, Gothic ubils), from PIE *upelo-, from root *wap- "bad, evil" (source also of Hittite huwapp- "evil"). In Old English and other older Germanic languages other than Scandinavian, "this word is the most comprehensive adjectival expression of disapproval, dislike or disparagement" [OED]. Evil was the word the Anglo-Saxons used where we would use bad, cruel, unskillful, defective (adj.), or harm (n.), crime, misfortune, disease (n.). In Middle English, bad took the wider range of senses and evil began to focus on moral badness. Both words have good as their opposite. Evil-favored (1520s) meant "ugly." Evilchild is attested as an English surname from 13c. The adverb is Old English yfele, originally of words or speech. Also as a noun in Old English, "what is bad; sin, wickedness; anything that causes injury, morally or physically." Especially of a malady or disease from c. 1200. The meaning "extreme moral wickedness" was one of the senses of the Old English noun, but it did not become established as the main sense of the modern word until 18c. As a noun, Middle English also had evilty.
Adolf Hitler is evil. Pol Pot is evil. Charles Manson is Evil. This employment of evil intends to communicate that these are bad (versus good) people. The intent is that these people are possessed by evil—as in an evil metaphysical spirit controlling these people. They were born with an evil soul. That’s how the term is typically employed, but this is a kin to a 4-year-old. Having yet to adopt the term, a child might, upon reflection, assert that these so-called evil people as very, very, very, very (…) bad.
One could argue that the term is shorthand for the 4-year-old’s version, but this missing the connotative subtext.
Nietzsche gave an interesting account of the origins of the term in Beyond Good and Evil. I recommend reading it along with the Genealogy of Morals. I don’t have more to add, but somehow got on this tangent after reading Nagel’s defence of religion.