The Pensees by Blaise Pascal seem to me much the best book about Christianity I have read; although it is hard to believe that I only encountered them in August 2010, so they have not had a chance to withstand the test of time for me.
I first heard of Pascal's Pensees some decades ago in reference to the 'wager' concerning the reality or existence of God; and knowing only this was enough to put me off reading the rest.
Because the 'wager' does not work under modern conditions, for people like me - modern society pre-immunizes us against any such arguments.
Perhaps mostly due to the fact that modern man is trained to believe that the concept of the soul is meaningless and there is permanent extinction of consciousness at death - therefore Pascal's wager works in the opposite direction from intended.
The 'safe' option of belief for moderns is therefore selfish, short-termist hedonism - on the basis that moderns only 'know' whether they are happy now and everything else is conjecture.
So Pascal's wager seems to suggest that it is 'foolish' to do anything other than optimize the current, here and now, state of well-being.
And because the wager does not work (stands no chance of working), or works in reverse; the fact that the wager is nowadays always linked with Pascal's Pensees serves to neutralize the whole book.
Which is useful for the powers of darkness if, as it seems to me, Pascal's Pensees is the single most important book of the truth of Christianity for modern people.