Are complement clauses that contain finite verbs be noun phrases? Consider English's "that" complementizer.
A. Clauses introduced with "that" can be be replaced with pronouns.
(1) I know that the insects will rule the Earth. --> I know it. I know this.
B. "That" clauses can also be subjects, objects, and complements of at least one copular verb.
(2) That Erin left Joe bothered me.
(3) I heard that Erin left Joe.
(4) Sue told me that Erin left Joe.
(5) The truth is that Erin left Joe.
C. But I can't think of an example in which a "that" clause can serve as an object complement.
(6) *I find the music that it sickens me.
D. And the choice of prepositions that can take "that" clauses as objects seems restricted.
(7) Everything was fine, except that Mary had fallen ill.
(8) *The apartment was okay before that the rats showed up.
E. And since when can a noun phrase have tense?
Part of my quandary may lie in my mis-analysis of some of the preceding sentences. Part of my quandary may have to do with the possibility that the choice of finite vs. non-finite complement clauses in given contexts vary from language to language.