Castles In The Air
It is a bit long, but it is in PDF format, so you probably better print it out before reading.
Also, I think it is a great starting point for UBF members.
If any UBF member is reading here, PLEASE, sincerely read this article.
If you know UBF members, give them that article.
Since it does not challenge any persons but a system with a different
name, UBF members will not have so big problems reading it. Also, the
article is written in a very humble and non-aggressive or arrogant way.
The article tackles some basic fallacies of the UBF such as "we don't
interpret the Bible, but simply obey."