Well, one of the problems, in no case the only one nor the most pressing. Merely a fundamental defect that renders the whole pile to rankest ridicule. Promising intro, isn't it ?
Very well, let's look at the christian system. So John the Christian does things. Not being crystalline shale, but live being, it's not possible to do nothing ; life depends on exchanges with the environment, and from there flows the obligation of action for any live thing, no exceptions. As such, John the Christian can't just sit suspended in stasis, but necessarily must do things.
Of the things he does, necessarily some will be "good" and some "bad", irrespective of what ethical system is chosen to add value tags to historical facts. This is so on one hand for the theoretical consideration that an ethical system devoid of category, one that either calls everything good or everything bad, would be trivial and therefore not worth the mention ; and on the other hand for the practical consideration that it is not possible to completely control material interaction (this being a law of mechanics, so however practical of a theoretical seed it sprouts nevertheless). We can't evaluate with arbitrary precision anything in nature, and as such no action will ever be crafted to perfectly allign with any theoretical model, system of values etcetera, never ever, whosoever and howsoever might try.
Here intervenes christian ideology, through the artefact of "forgiveness". I've said before the notion means nothing to mei, but in xtianism it works something like this : if John the Christian does something, and later comes to think he shouldn't have, and if he "sincerely regrets" the deed, it is "forgiven".
What does this mean ? Well, the first nebulous concept, "sincere regret", is in fact insurance against man's will : the system of christian forgiveness does not wish to work except in those situations where its functioning will not be used to prove... its dysfunctionality. A sort of "we'll sell you cars only if you promise under pain of annulment of the sale that you won't use the cars sold in any way which might prove the thing we sold you isn't a car". That's the basis of the "meeting of the minds" involved, xtian "forgiveness" demands as its only precondition the warranty of the potentially-forgiven that he won't rely on said forgiveness in any kind of dispute with the system.
In the simplest presentation, this wonder works thusly : if John goes to the priest and asks for forgiveness, after which upon being so forgiven turns around and points at the idiot in funny costume and laughs and tells him "ha-ha, I'm going straight to the brothel, dumbass" the professed warranty of "sincere regret" somehow manages (in the "reasoning" of the christian, I am not responsible for their idiocy) to retroactively annul the fact of forgiveness (which in turn was the retroactive annulment of the fact of sin).
So, in the thermodynamic flow of events, every proposed "act" of forgiveness creates a bifurcation, and it is proposed to be established at an ulterior moment whether the forgiveness "held", and the deed forgiven is in point of fact undone, or conversely if the forgiveness was anulled, however factual it might've been at the time of its occurrence, and by way of consequence the deed it purportedly annulled is un-undone. For better idiocy, the moment at which the fork is to be resolved isn't even fixed in time -- and this, even if not by a longshot the only problem, is nevertheless a very serious one.
For instance, inheritance vests into title within a specific, maximally fixed term ; wills that purport longer intervals (or just the lines in question) are routinely stricken. "No interest is good unless it must vest, if at all, not later than twenty-one years after the death of some life in being at the creation of the interest." says the Englishman of 1500, to avoid the situation of mortmain, but the christian doesn't have that minimal understanding of things and matters in law (discussed here as a theoretical possibility of legal working, nevermind practical applications) as'd befit a medieval legal scholar. As such, there's no RAPii among the xtians, I can pull out the proof Mary was a whore and never actually regretted it sincerely (but instead simply lied to everyone about it) whenever I fucking feel like so doing, and blam! there she flies out of Heaven, to the consternation of the whole body catholic.
A more serious problem than this issue of vesting repentance is the problem of broken idempotence. As you perhaps know, everything in nature balances out, every action with its reaction, every interior with its exterior, every "up" must have its "down". Anything that can be accelerated can also be decelerated, anything warmed can be cooled, if you lift water here you lower something somewhere else and so following.
Christianity hasn't quite managed, on the piddly impetuus of its scant brain poorly employed, to comprehend this basic property of the world, so therefore sins can be forgiven, but achievement can't be... forgiven. Logically it would be required, by the doctrine of annulment of fact by faith (call it "repentance", or whatever theologico-religious bullshit you prefer) that any facts be annulable. For instance, John the Christian trains dedicatedly, works for years day by day, ends up an olympic runner, runs very well one peculiar day, is a hint lucky too and gets first place. Good for him. Good for him but tough tits, because looky I sincerely repent his victory, and it's thereby annulled. Buh-bye.
The circumstance whereby this device of "forgiveness" is to be opposable to third parties, per the lights of xtian idiocy, but third parties don't have an equivalent system whereby to oppose our deeds produces necessarily and as it must a most significant imbalance, which works to reduce the importance of our own failures to nil, and through this moral hazard, cosubstantial to and entirely produced by christianity, utterly corrupts the faithful. Sooner or later any true christian will be mendacious, bigoted, jealous, and generally speaking driven against the other -- because you can't possibly give anyone a button which reduces the other to nil and expect them not to use it to infinity. No matter how well the story begins, however elegant, generous, loving or honest may the hero start off, through christian practice he will necessarily if by degrees arrive to moral decay, because that's how christian ideology is constructed, to corrupt.
Seeking some respite from this fundamental problem rivers of ink flew, whole forests of innocent trees were pressed into countless tons of useless maculature, billions of spoken evening entertainments were produced and consumed in halls set aside for the purpose of spoken evening entertainment. Sadly one can't mend a tear in the space-time continuum with needle and thread, and similarily one can't repair the fundamental immorality of christianity by superficial moralizing. The two principal avenues through which fixing is attempted but not succeeded are the doctrine of love and the theory of nonlegalism (which is to say the fanfic view whereby ethical considerations supersede legal considerations aka the "people themselves" argument, or "willing suspension of disbelief" if that's the label you prefer). These two aren't just systematically neglected in practice (for their own fault, being as they are self-contradictory and unmeasurable nonsense), but in spite of their not fixing anything nevertheless they manage to create all sorts and manner of other problems, so intricate and far reaching as to make their complete avoidance a much cheaper solution, normatively speaking.
In the end, the imbalance we're discussing is the driving force for the insurance mechanism we discussed further up. Not that it could possibly serve anything to have meaningless warranty in support of a system that's systematically dysfunctional, but hey, people try.
May it stand for their eternal happiness, that trying, but I'd prefer to hear no further whines about how "people are bad / the world is evil / sinful" blabla etcetera. The problem isn't the people, the problem is the nonsense thought by boots calling itself christianity. I don't necessarily hold the original authors responsible, because what can be expected of a bunch of unwashed orcs shepherding goats ? In any case not operating systems for numeric machines, an infinitely easier task than what they pretend to have achieved writing "the bible". I do however hold the belated idiots responsible, the sort of moron trying to run GoatSmegma '00, the Jerusalem edition on 64 bit processors. It's fucking inadequate, derps, how about an upgrade ? Try Popper, it's open source.———