Professional educators are required to take regular training classes in order to retain their teaching license. Yet, we will allow volunteers to teach children and teens about God with little if any training at all. Most of the time, we have no idea what happens in the classroom after volunteers begin teaching.
Unless a parent complains (and most don’t because they are rarely heard), your volunteers could be teaching or doing anything (or nothing at all) and you would have no idea. The horror stories I hear are everywhere and in most cases could have been easily prevented with volunteer training.