Complex sentence: At that time Zeitgeist was a promoter-advocate of the Venus Project, however, in April 2011, the Venus Project formally disassociated itself from Zeitgeist as it no longer felt represented by Zeitgeist.
Split into simpler sentences: At that time Zeitgeist was a promoter and advocate of the Venus Project. In April 2011, the Venus Project formally disassociated itself from Zeitgeist as it no longer felt represented by Zeitgeist.