The group uk.religion.christian , which I read frequently, is excellent with a high level of serious discussion. Other religious groups I read are soc.religion.christian , bit.listserv.christia and alt.religion.christian.biblestudy . Always read a newsgroup for a few weeks before posting to it for the first time. If you are an established contributor to a group you will get substantially better responses when you talk about specific areas of Christadelphian belief. There are some topics that, through experience, I instinctively avoid on newsgroups.
Some topics generate nothing but heat and lead to no profitable discussion.
Experience will show you that there will always be topics where the discussion is high quality and it is much better to concentrate on these. Newsgroups are an excellent forum for the discussion of our beliefs, and strongly encourage everyone to use them.