Romans 1:28

ἐδοκίμασαν, ‘they thought not fit’ (cf. Field, ad lo[77]). The verb implies approval after testing: the infinitive is epexegetic. τὸν θεὸν closely with the verb; cf. in passive construction 1 Thessalonians 2:4. They tested or proved GOD and decided not to keep Him, etc.

[77] ad loc ad locum

ἔχειν, pres. = to keep, maintain what they had received. ἐν ἐπιγνώσει = rather ‘intimate’ than ‘full’ knowledge, close application of mind rather than mastery, though the latter follows in due degree. cf. Robinson, Eph. 248 f.; Moulton, p. 113; cf. Romans 3:20; Romans 10:2; Philippians 1:9; cf. 2 Corinthians 13:5 f.

ἀδόκιμον νοῦν—νοῦς the mind as originating purposed action, good or bad. ἀδόκιμος, unable to stand the test which is properly applied to it; cf. 2 Cor. l.c[78]; Hebrews 6:8.

[78] l.c. locus citatus