Citing competing books in my book

I’m writing a nonfiction Christian book about prayer. I am getting near to done, but I”m going back and looking for quotes to add to the chapters. I’m not sure, but I think I need more endnotes. Is it a bad idea to quote from a book that is a competitor? I’m also unsure about my endnotes in general. InterVarsity Press told me for a book I co-authored with them that readers are afraid of footntoes. I don’t understand that, so I wwonder if a few more would be good or bad. I’ve got many nonacademic nonfiction Christinan books that have 5-10 footnotes per chapter. As an academic, I wouldn’t touch a book like mine without endnotes because I would assume the author invented everything out of her/his imagination. This is my last step before sending the book to a professional editor. I’m tired of being almost done, but I don’t want to send out somehting readers won’t want. No, I haven’t found a good Timothy. I had one but he became unreachable. Thanks.