is a clear case of preaching to the converted 
(ROOT (VP (VBZ is) (NP (NP (DT a) (JJ clear) (NN case)) (PP (IN of) (S (VP (VBG preaching) (PP (IN to) (NP (DT the) (VBN converted)))))))))
(ROOT (VP (VBZ ) (NP (NP (DT ) (JJ ) (NN )) (PP (IN ) (S (VP (VBG ) (PP (IN ) (NP (DT ) (VBN )))))))))