Thank you for the comments, Reverend!
Personally, I don't think religions such as Christianity are "a necessary evil" so much as they are inevitable byproducts of human society. I've seen many atheists who think that most of humanity's problems would go away if you got rid of the spiritual religions, but I really don't think so. People would be just as stupid, and more importantly will still have the biological hard-wiring for projecting patterns on to things and forming ritualized expression. If Christianity went away, the herd would just create and cling to some other sort of ideology. In most cases, they already have.
To be entirely honest, I once thought I believed in the christian god, with some caveats. Firstly, since I had actually read the bible, I understood that no amount of creative interpretation could convince me that mainstream christianity actually followed what was written in the book, and thus I could not reject god based on the hypocrisy of those who claimed to follow him. Secondly, revelations clashes so dissonantly with the rest of the bible that it should be obvious to anyone that's read it that it doesn't belong. Discounting revelations, it's interesting that all miracles in the bible were natural phenomena. Lightning striking ark-fondlers, the parting of the red sea, the burning bush, earthquakes, etc. are all improbable, but not impossible. Thus, if there existed a god, I thought its true power would be manipulation of probability. In reality, miracles are mere coincidences in which statistically unlikely events occur in a manner that suggests an external will.
Also, as you point out, the details of Christianity have changed a lot from century to century and culture to culture, so this begs the question of how exactly we'd recognize the "death" of Christianity. For example, I'd say the Christianity from 500 years ago is essentially dead.
As founders of christian offshoots have no doubt realized, the christian herd will follow nearly any set of guidelines delivered to them by a charismatic, intelligent individual, even if those guidelines are in direct contradiction to the bible. All one must do is quote the right passages and work the crowd into a fervor. Appeals to logic will always fail, but splashing the crowd with a new color of crazy just might change the overall hue to something more tolerable.
Actually, I think Christianity is already doing a good job of destroying itself. Fundamentalists like Fred Phelps and charlatans like Benny Hinn do more to turn people off from Christianity than I could ever hope to on my own! And of course, there are other religions to deal with too. Religiously speaking, I'm just as anti-Muslim or anti-Buddhist as I am anti-Christian.
I got my books today and the fact that most religions advocate universal abstinence has certainly been a central theme. As I said before, I grew up in an area where nearly everyone was christian, and even though I was not, all the young christians indulged themselves in 'sin' much more than I did. I sometimes regret not having more fun, but then again I am pleased with my current situation, so regret is pointless.
Maybe abstinence was useful when people had little, and little more was in reach, as it kept the poor and hungry from reaching too far. Fasting (being hungry) is a spiritual experience, Jesus did it for 40 days! Are you poor? Well, I've got the deal for you! The poorer you are in life, the richer you'll be in heaven (yes this is in the bible)! Hallelujah! The herd is now wealthy, so there's no reason for abstinence, hence the redefinition of christianity.
The only thing the christians have left to defend is the chiefest of the 8 deadly sins, homosexuality.
Pride? Be proud that you are christian, as it automatically makes you better than everyone else!
Gluttony? Accept the fat for who they are, they cannot help but eat!
Greed? Give to the church, but keep enough for yourself to buy your Sunday best!
Sloth? Don't work on Sunday, Sunday is nap-day!
Envy? The other church bought a big screen T.V., so let's buy two!
Lust? Bring more christian children into the world, even the pastors are all married!
Wrath? Turn the other cheek, unless you find something offensive or something makes you uncomfortable, then destroy it!
Homosexuality? I found this part in the old testament where people were gay and god killed them. Please ignore the part about slaughtering the women and children of your enemies, that part doesn't count. Also, although there is no mention of women laying with women or god having any kind of beef with that (the bible is specific to 'men laying with men'), lesbians are bad too.
Once that's gone, what do they have left? What will be the 9th deadly sin?