Originally Posted by Theoboldi
...the Forgotten Realms Campaign setting from 2001 still mentions the Wall of the Faithless.
The Faithless are discussed in several paragraphs on p. 259 of the FRCS. The Wall isn't mentioned by name as "Wall of the Faithless," but the Faithless are described as forming "a living wall around the City of Judgment, held together by a supernatural greenish mold." The mold apparently immures them in the wall and eventually dissolves them into nothingness.