Original sentence: Brown's theory is described by a supporter as "a hard-line exegetical approach to the text of Genesis" that "directly challenges the current plate tectonics model of large-scale geology" -- a theory that is still disputed
Edited sentence: Brown's theory is described by a supporter as "a hard-line exegetical approach to the text of Genesis" that "directly challenges the current plate tectonics model of large-scale geology" -- a theory that is fraught with problems (See External Reference section below)