Byron Williamson, president and publisher of Worthy Publishing, makes quite clear who first came up with the “Killing Jesus” book title. “The night we found out about O’Reilly’s book we were uploading our files at that time to the printer,” says Williamson. That book is “Killing Jesus: The Unknown Conspiracy Behind the World’s Most Famous Execution,” by the much-published author Stephen Mansfield. It’s due out in May.

“We conceived this book probably in the first half of 2012, a year ago — so long before we knew anything about O’Reilly’s book,” says Williamson. The full title of O’Reilly’s book is “Killing Jesus: A History.” It’s due out in September.

Can O’Reilly really do this under the law — just use the same title? Absolutely: Titles of single, or one-off, works  generally are not protected under trademark law. For instance, search for “America at the Crossroads“; some results pop up.

O’Reilly is a formidable author with whom to share a book title. His previous “Killing” books, on the Lincoln and Kennedy assassinations, staked out prominent and long-running positions on the New York Times hardcover non-fiction best-seller list (in the latest iteration, “Killing Kennedy” is No. 3 and “Killing Lincoln” is No. 12). In the words of the Times, he has become “arguably the most popular history author in America.”

So do the non-O’Reilly “Killing Jesus” people worry that the O’Reilly book will hurt their volume? Or help it? Neither, as it turns out: “After thinking about it, we saw it as sort of a neutral thing,” says Williamson. “We ended up thinking it may not make any difference at all.”

Nor is the Stephen Mansfield “Killing Jesus” project trying to piggyback on the commercial success of O’Reilly’s “Killing” thing. When they hatched the idea for their own “Killing Jesus” project, says Williamson, O’Reilly’s works weren’t yet a series. “We didn’t know about ‘Killing Kennedy,'” says Williamson, noting that they were aware only of “Killing Lincoln.”

Being first to “Killing Jesus” has afforded Williamson and Mansfield superior web optics. Their book can be found at the simple and intuitive; O’Reilly’s version can be found at the slightly less simple and intuitive