I think Chinese philosophy held China back technologically, (And thus made them subject to the dictates of English Guns) but I think what made Opium addiction such a devastating factor in China's history is the fact that the substance is physiologically addictive to humans.
But you touch on a point that I have been pondering for some years; The Role of Christianity in making this nation great. I've read quite a few articles (Starting with De Tocqueville) asserting that it is our Christianity which made us great, and i'm beginning to think it is indispensable to a functioning society.
I ran across this article some months back, and I noticed this one today.
I am coming around to the idea that Christianity (or something very like it.) is a requirement for a functional society. People do not realize how it affects social interaction throughout the whole system. Now that it is in decline I suspect society is going to get a lot more vicious.
Buddhism served an earthly role like that in some countries; and Hinduism in others. But neither has a robust gospel like Christianity does.
And this is really true. Your proverbial Diogenes would be hunting forever in vain unless he met Jesus. Nobody’s utterly honest, though some come much closer than others.
However the classic Christian gospel preaches a God of both heavenly ideals and of second chances. This God when embraced can remove great amounts of evil.
And, it’s not just a nice story. I’ve watched the spirits told about by the bible actually working as documented. Both evil (hellish) ones and heavenly ones.
But in America when opium was legal, addiction was low and declining. The DEA says, "In 1880 [...] there were over 400,000 opium addicts in the U.S. [...] By 1900, about one American in 200 was either a cocaine or opium addict." (http://web.archive.org/web/20110529221013/http://www.justice.gov/dea/demand/speakout/06so.htm) 400,000 in a population of 50M is one in 125 - ergo, between 1880 and 1900 addiction declined.