I would never deny that Christianity is ultimately a faith that proclaims a hopeful, joyful, and comforting truth: Despite so much apparent evidence to the contrary, truth can be found, we can be cleansed of sin, and life can end as a comedy (with marriage--in this case, communion with God) and not as a tragedy.
But. To fully imagine the inner life of a Christian, I think it's necessary to acknowledge that there are doubts, terrors, and pains that are as native to Christianity as the corresponding terrors of an atheist are native to that belief. I find it much more terrifying (and difficult, not philosophically but personally) to believe in Hell than to believe in nothing after death. This is one of the things that keeps me up nights. I think that, overall, I'm happier now than before I converted (in large part because I'm morally steadier--yes, I know, but you didn't know me before! We're working from a low platform here, people...), but there's been a lot of tumult, upheaval, and drinking-in-self-defense. It is often difficult to believe, to trust, the promises of Christ, no matter how good your philosophical reasons for faith. The joyful aspects of Christianity must also be struggled with, and struggled for. Mother Teresa knew this from her own experience.
I notice a similar worldview in the women I counsel at my volunteer job. The belief that it's the comforting or joyous parts of Christianity that are hardest to believe is not unique to overeducated ex-atheists. Many of the women I counsel find it all but impossible (that "all but" is crucial...) to believe that God loves them; that living as a faithful Christian is possible; and that they have enough strength to live rightly. They're not "leaning on the everlasting arms"--they're struggling to escape what feels like God's vise-grip. I remember riding on a Metrobus in 1997, when I was first beginning to realize I might have to enter the Church, and literally feeling like it was hard to breathe because I felt so trapped by the philosophical and experiential evidence for Christianity. Now, I can find comfort in God's presence, even if I also find fear or doubt; but not in 1997.
Another way of looking at this - which I think Eve is getting at - is that the Christian experiences both the worries and doubts and terrors native to Christianity and many of the terrors native to atheism. We're just as likely to oscillate between the fears Eve describes - of unworthiness, of damnation, of losing too much of ourselves if we surrender to God - and the fear that there is no God at all and life ends with death and annihilation, as we are to bask in the comforts of the Easter story. We're enjoined, of course, to be not afraid, but we're also informed at the fear of the Lord is the beginning of wisdom, and many people - myself included - don't get too far past the latter point. (I said earlier that the idea of the resurrection of the body and the life everlasting corresponds to my heart's deepest longings, but that doesn't mean that I feel at all secure about it.) There are fearless Christians out there: we call them saints. But even the saints have dark nights of the soul, and in the rest of us fear and hope, doubt and belief, are intermingled till the end.
But then again perhaps they're intermingled in the atheist as well. This is the current Pope's argument in his Introduction to Christianity - that "on both sides" of the gulf between believers and unbelievers, "the same forces are at work, if in different ways":
The believer is always threatened with the uncertainty which in moments of temptation can suddenly and unexpectedly cast a piercing light on the fragility of the whole that usually seems so self-evident to him .. [but] even the non-believer does not represent a rounded and closed existence. However vigorously he may assert that he is a pure positivist, who has long left behind him supernatural tendencies and weaknesses, and now accepts only what is immediately certain, he will never be free of the secret uncertainty whether positivism really has the last word. Just as the believer is choked by the salt water of doubt constantly washed into his mouth ... so the nonbeliever is troubled by doubts about his unbelief, about the real totality of the world which has has made up his mind to explain as a self-contained whole.
"In short," Benedict - then Ratzinger - concludes, "there is no escape from the dilemma of being a man." Which is a pretty good way of putting it.