Firstly, my standpoint. I'm an agnostic
and an atheist. (Atheist as in not a believer, not as in a denouncer/disbeliever. The distinction needs to be made. Tag me as an "implicit" (rather then "explicit") or "weak" (rather than "strong") atheist, if you want to use either of those terms to qualify me. (And this is the biggest misunderstanding I think needs to be addressed, as not everyone who necessarily says "<given religious stance> can't be proven" is saying "<given religious stance> is
wrong".)
The most common argument I've seen in response to [why is there evil] is that God also wants people to have free will for some reason, and since humans are imperfect they sometimes chose to do evil.
Taking this from my POV, in which my logical equivalent to "God created us all" is that we are simulations inside someone else's computer (to vastly simplify the analogy, which can easily accommodate the idea that there
is a God, i.e. the operator), the creator involved is surely omniscient and omnipotent as he can peek and poke any bit of data within His simulation, but omnibenevolence isn't a factor because the deterministic universe he has set going (except where He deliberately disturbs it by making data changes) is just a Conway's Game Of Life to Him.
There's loads of complex patterns, interacting, but by
His standards any entities that (to themselves) proclaim self-awareness are just as much a complex of interacting patterns as the rest of the interacting patterns that form the 'universe', whether sentient, non-sentient-but-living, mineral, astronomical or (because some patterns will encode for the non-physical) informatical. Any strangenesses (miracles, divine interventions, deluge-equivalent overturnings of the entire world, etc) that the entities observe are unlikely to be conscious attempts at communication and direction from The Creator, but the same sort of experimentation as
we are likely to perform upon any similarly abstracted simulation within
our computers. And you just know how
you would either get bored and mess about a lot (probably wiping out any 'conscious' entity you inadvertently and unknowingly produced) or just let it run and see how it goes until you
do get bored, or need to reboot the machine. (As far as our world is concerned, it appears that we've been left to run, on the whole. But that's just my own surmising based upon our possibly deceptive experiences (see below). Thus we are pretty much deterministically following paths, and Good and Evil are of no concern to Him, whoever He is, or even conceived by the respective Almighty for being the events and deeds that they 'are'.)
That's assuming the Creator is not omni
understanding, of course. An omniunderstanding Creator would not just have the simulation in front of him, but also have a version of the simulation being thought through in His own brain (or equivalent) in order to be able to go "Ah, I see, this is a sub-entity who is starting to understand the nature of Me, and I were to arrange for something to happen to him, this understanding would grow (or change, or diminish)". In constructing these thoughts, the relevant bits of simulation would exist within the
head (or equivalent) of the Creator, and given the usual parameters ascribed to Him I would have no hesitation in describing
that simulated reality as being as real as the simulated reality in His computer. In fact, one could go further and make it a full 'thought experiment' within the Creator's mind, and that is where we exist and live.
Whether or not the "thinking Creator" is Himself perfect, we can imagine that the reality we see now is as a result of the thoughts that lead up until 'now'. There may have been "how about if I do <this>", and then back-trackings to see what happens if <that> is done instead (this also applies to the machine-only simulation version, if we allow the concept of saves and restores of prior 'game points'). Indeed even the
current time-stream may be of a "let's see what happens if I let the world follow this path", but may shortly be aborted and our entire existence redone (or re-redone) down an alternate path with different Divine Interference at its route. Under
this conceit, the answer of "Why does evil happen" is "to see what happens if these consequences play out". And either the result is that these consequences are rejected and are retroactively changed or they are accepted as
necessary acts towards the fulfilment of the world He wants to result.
(To analogue to the Real World (by some worldviews), maybe Adam and Eve could have been kept from exiling themselves from the Garden Of Eden, but that would have just produced an eternal Garden Of Eden with forever innocent inhabitants who did nothing actually worthy of His Glory, in the way He wanted. Exile, with all the theatre surrounding that act, allowed the creation of large populations of His created beings who could (on the whole) progress through to the legacy wished for, for His own ineffable reasons.)
There's perhaps a further development of the idea, the "omnipredictive" Creator, but I would rationalise that this is virtually the same of the branch-simulating one, or (if He doesn't interfere) just one who has run through the way his Fire-And-Forget scenario will run and accepting that result. It might seem rather pointless, though, to 'run it again'. But, as I said, He probably has ineffable reasons behind it. We could never know the motivations behind any Greater Being.
Personally, I see no reason to suggest that there's a guiding force
at all, save for celestial (or, rather, pan-universal) mechanics, much akin to what we abstract down to "The Laws Of Physics", but whether the simulation was intelligently configured, intelligently (or otherwise) guided or just happened because "the 'universe machine' just happened" is irrelevant to my own philosophy. Of course, this posits that Evil happens because it's a natural result of the universe's progress. Not much comfort, there, but neither is there any soul-searching of why He has allowed it to happen, and the best can do is Deal With It. Which, incidentally, is what I think He wants us to do, anyway, should there be any He existing.
I can also imagine a God Of Logic. This god creates the universe, either as we see it or in a Young Earth Creationism manner but in the form of an older universe that arose in some given logical manner (with all the trimmings of "old photons that had 'already' set off from stars that have only now started to exist", or even "have existed, but are now their remnants of a star's dying, as to be later observed by 'younger photons' placed further back in the light-trail"). We could presume that His aim is that all His creations are expected to observe the (false, but realistic) scientific logic behind the universe and that those that He would favour are those that follow the logic and believe the universe to be 'atheistic', while those that ascribe to any religious perspective are given His equivalent of Damnation (including, of course, those that, for no actual reason, believe directly in Him, the God Of Logic!) But that gets rather meta.
)
((And while we're being meta, in various YEC beliefs, the world was created recently, and any "older things" were created old, as part of the Divine Illusion that we are meant to see through (except in the GoL's case, of course). To
create the older things, the deity concerned must have "run through" the world/universe in His mind in order to construct realistic strata and cosmic features and the like... Taking us back to the different forms of Creator already mentioned, can we not imagine that
we are still within His imagination, as he gets together the imagined events that will lead towards the
future creation of a Young Earth world, with 'us' as background. To parody the already paradoic "LastTuesdayism", this can be dubbed "NextTuesdayism". The questions about Good and Evil are of course similarly irrelevant (or at least unanswerable) as with all the other "we're a simulation/thought experiment" versions so far discussed.))
Now, another thing I've seen talked about somewhat less often is the 'Christ died for your sins' thing. Specifically, what does Jesus dying have to do with people sinning?
I shall be briefer, here. My understanding is that (allowing for various aspects of determinism and whether Christ Is God or Son Of God or both at the same time within the Trinity) it is taken as a juncture. A point in time between which the (perhaps necessary) Old Testament mode of Godliness and the New Testament methodology. This can be interpreted in many different ways, according to one's own particular faith (Mohammedan believers
probably go for their own later "point of inflection", etc), and I doubt I could cover them all sufficiently accurately, so I'll leave it at that. "Believing in Jesus" is (while not
actually a central tenet of
all Christian sub-sects, strangely), fairly tautological, as well.
Anyway, I see many other people have posted in response, and I posit this only as my interpretation, from both my own 'belief system', plus as many variants (which I hope include scenarios that those of
actual faith can grasp the meaning of, albeit without full agreement as to their validity. Although I was perhaps a little heavy on the whole "nature of Creation" at the top, sorry. (And never even touch upon the "who/what created the Creator" question, but I know you're not asking about that.)