The moderators found it difficult to keep watch over a multiplicity of forums. Moreover, the sub-forums were a drain on the main NCR page, so that Non-Catholic Religions was seeing very little interesting activity. Combinine the forums put some life back into the NCR forum.
Flameburns has pretty accurately explained it. I’d just add that all the threads from the sub-forums were collapsed back into this parent NCR forum, except those from the former Eastern & Oriental Orthodox sub-forum. That sub-forum was upgraded to a forum of its own and broadened in scope and title to encompass Eastern Christianity.
DISCLAIMER: Catholic Answers has turned over the archive to Catholic-Questions.org and no longer owns, manages, or moderates the forums. For additional apologetics resources please visit www.catholic.com.