By well-doing (agathopoiountas). Present active participle of agathopoieō, only in lxx and N.T. (Mar 3:4). In accusative case agreeing with humas understood, accusative of general reference with phimoin, present active infinitive (epexegetic infinitive after to thelēma tou theou, the will of God), late and rare verb (from phimos muzzle), as in Mat 22:12.
The ignorance of foolish men (tēn tōn aphronōn anthrōpōn agnōsian). Agnōsia is late and rare word (in the papyri) from alpha privative and gnōsis (knowledge), in N.T. only here and 1Co 15:24 (disgraceful ignorance in both instances). Note alliteration.