I would say there is no bias, both are equally interested but in different ways.
Christians are interested in the end of time prophecies from the Bible, but not in other sources (e.g. they would reject the Mayan calendar theory). Non-Christians, if they follow another religion, may have their own end time prophecies. In contrast, prophecies such as the Mayan Calendar and the other end-of-world scenarios such as whatever date it was incorrectly theorized in 2011, would appeal more to atheists than anyone else.
In a nutshell: I truly don't think any group is more or less interested in the end of time prophecies, just that the source of the prophecies will differ.