on non-fiction reading group?

You will be literate citizens. Who better than you to read the books, discuss them, arrive at your conclusions, and let the author worry about whether (s)he made the material clear to you? At the end, you will all be the experts. Just don't let any one member monopolize the discussion.

That is one reason to take college courses.

When you take upper level history courses (Or any of the Humanities), much of the value comes from having an intelligent group of people who have all read the same material and are willing to discuss it. Quite often, the professor is the one most excited by such discussions.

Three components to your situation: your average member; the book(s) on the topic(s), and truth-discernment.

Hence, if you read a book that your members are able to evaluate truth-wise leading to some (to you all) satisfactory degree(s) of ontological and epistemological certitude, that is an appropriate book.

Examples:

"West with the Night" is excellent nonfiction, and able to be evaluated in terms of personal experience and historical veracity, by most lay readers.

"Autobiography of a Yogi" is excellent nonfiction, and is able to be evaluated in terms of personal experience and veractiy by other, spiritually discerning readers.

Therefore, the first book is definitely suitable, while the second would appeal to those who have a level of ability in that particular subject (spirituality).

More finely, "Autobiography of a Yogi" is a spiritual document; "The Truth Jesus" is nonfiction about spirituality, and thus would be acceptable to all readers, as one need not have a level of discernment or interest in Spirit that e.g. "Autobiography of a Yogi" or "The Path of the Higher Self" present. I.e., there is no argument about the facts in "West with the Night;" "The True Jesus" is a "travelogue" like Bill Bryson's "In a Sunburned Country;" only mild or academic interest is asked, that good discussions may occur. When one moves to an area in which a book is "doing Spirit," or "doing physics," that asks of the reader some genuine interest and ability to discern truth, vis a vis group discussions. Basically, your question relates to the distinction between amateurs and professionals, and intelligent levels of discussion.

The books you choose don't have to stress factual accuracy. A memoir, for example, is a nonfiction book that doesn't require you to verify the facts. (It's true that sometimes memoirs have been exposed as being fictionalized, but there are plenty of authentic memoirs to read. In any case, a memoir is one individual's description of his or her experience; someone else would have different experiences of the same events.) If you pick a book by an acknowledged expert or a respected writer, then you don't have to wonder whether the book is accurate and can just concentrate on the content and what you get out of the book. With any nonfiction book, one could always raise some kind of doubt: for example, the facts might be all correct, but the writer may have presented them in a manner that puts a slant on the way your opinion is formed. There's not much you can do about it, so it should not be the aim to try to evaluate the exact factuality. And if doubt is cast on any important fact, it's easy enough to research it online.

I think your discussion can consist on the basis of the book you are reading. Take it like a friendly discussion with people you have known forever. Number one thing is to be comfortable around these people since you are starting a group. Not everyone will agree, but it is fun to see other's insights on the subject. Don't make it complicated, no one wishes to feel like they are being quizzed at a friendly group. It is a chance for each person to grown and enjoy each others company.