According to a Pew research study, atheists and agnostics scored better on a religious knowledge survey than other denominations, and Jews and Mormons scored higher than Christians:
Overall, the three groups that perform best in this survey are atheists and agnostics (who get an average of 20.9 out of 32 questions right), Jews (20.5 questions right on average) and Mormons (20.3 questions right). Looked at another way, 27% of Jews, 22% of atheists and agnostics, and 20% of Mormons score in the top 10% of all respondents in overall number of correct answers to religious knowledge questions, getting at least 26 questions right. As will be discussed in detail later in this report, these groups display greater religious knowledge even when education and other factors are held constant.
This report was from 2010, so it’s not clear how agnostics and atheists would fare today, but it’s probably safe to say that they would still score higher than all religious groups in answering questions for a similar survey.
I’ve found that in many cases, one reason that nonbelievers reject Christianity or Judaism is because they have actually read their religious texts and studied them more closely than evangelicals. For instance, while a believer, I can’t say that I had ever heard about the crude little story about 42 children being mauled by bears for the minor offense of making fun of a bald guy. Too silly for God’s special book? Nope. Right there it is in 2 Kings. Nor did we ever spend much time retracing the moral lessons behind Lot’s daughters getting him drunk and then sleeping with him. Or, that time Noah got plastered after landing his ark. Or, that part about stoning women believed to be witches. Or, that part about stoning gay people or the commandment against eating shellfish or … You get the picture. By and large, believers are so enamored about what they perceive to be the “good” parts of the Bible, they willfully ignore the absurdities that drip from nearly every page.