Where can I find the Sunday Without God light novels in English?
There is no licensed English translation of the Sunday Without God light novels. There probably never will be, since the show and the light novels are at best moderately popular in Japan. 

Site policy is to not link to fan translations, so I'm just going to wink in the general direction of Google. (But you're not going to find much - the fans don't appear to be interested enough to translate the novels either.)