Major religious holidays at least tend to have some good stories behind them. You can enjoy the story even if you don't put much stock in it as either the truth or the Truth. There's no single reason that forced me out of the Christian fold, just a whole bunch of compelling reasons. An early seed of doubt came from the resurrection story itself. Even a layman like me could spot the differences between the Gospels. Once I realized the conflicts within the founding stories of the faith, taking the entire thing seriously became progressively harder for me. I gave up the religion, but I kept the stories.
They're some damn good stories.
Perhaps I am an odd atheist for enjoying bits and pieces of the Bible, but parts of the no longer holy-to-me book still inspire me. I read Ecclesiastes for both pleasure and wisdom. We all could do a lot worse than to live by the Beatitudes (and a number of purported believers might be better served to spend more time reading the Sermon on the Mount and less time with selective contemplation of Leviticus).
The story of the supposed Resurrection may not hold up, but I appreciate the passion of the telling. The anguish in the Garden, Peter's denial, the grief of the women, the pronouncement by the angel--it's a compelling story in each of the mutually conflicting versions. I can see how the tale caught on, especially in an oral age.
I'm not a Christian, but I enjoy a good story. I'll read the Gospels tonight, for old time's sake.