I like new words. They show up to describe things that:
- didn't previously exist.
- hadn't been described in a certain context.
- just plain old wanted to be described in a new (and often fun) way.
I don't like new words that show up for no reason whatsoever other than people thinking they're using a real word.
Credence is a word. Credulous is a word and so is incredulous. Likewise credulity and incredulity. These all spring from the Latin credentum (nom. credens), pp. of credere "believe, trust." Also useful are credendum, credent, credential and credible.
I can't find credulence in any dictionary. A web search brings you here. Note that the first thing at the top of the page is a helpful prompt asking you "Did you mean credence?" The first few links are to things on Amazon and Live Journal, so that's just people writing crap. Wrongly, but hey, I can live with that.
I'm less than happy with fifth hit on the page. That's a link to an entry on the Education Resources Information Center, part of the U.S. Dept. of Education.
Dear Dept. of Education. Credulence isn't really a word. Credence would have worked fine in its stead.