Here's how the Oxford English Dictionary quotes Lederman:

"As for the title, The God Particle, my coauthor, Dick Teresi, has agreed to accept the blame... I mentioned the phrase as a joke once in a speech, and he remembered it and used it as the working title of the book. 'Don't worry,' he said, 'no publisher ever uses the working title on the final book.'

"Why God Particle? Two reasons. One, the publisher wouldn't let us call it the Goddamn Particle, though that might be a more appropriate title, given its villainous nature and the expense it is causing. And two, there is a connection, of sorts, to another book, a much older one."

He apparently didn't say exactly what he thought that connection was. And even later he thought that "Goddamn Particle" was the more appropriate name.