As a benchmark for cultural religious literacy, take this quiz from Pew's Religion and Public Life Project.
You'll be surprised at how easily you'll be in the top 1% of Americans for religious knowledge.
Here's more thought fodder on the topic:
The Atlantic:"Study Theology, Even if You Don't Believe in God"
The New York Times:"The Book of Books: What Literature Owes the Bible" (Old, but oh-so-good).1