Romans 10:2

Their good qualities compel his affection. ζῆλον θεοῦ ἔχουσιν : they have a zeal for God, are intensely (though mistakenly) religious. Cf. Galatians 1:14. An unbelieving Jew could interpret his opposition to the lawless gospel of Paul as zeal for the divinely-given rule of life, and his opposition to the crucified Messiah as zeal for the divinely-given promises. It was God's honour for which he stood in refusing the Gospel. ἀλλʼ οὐ κατʼ ἐπίγνωσιν : this religious earnestness is not regulated by adequate knowledge. For ἐπίγνωσις see Ephesians 4:13; Philippians 1:9; Colossians 1:9-10; Colossians 2:2, 1 Timothy 2:4; 2 Timothy 2:25; it is especially used of religious knowledge, and suggests attainment in it (ἄρτι γινώσκω ἐκ μέρους, τότε δὲ ἐπιγνώσομαι, 1 Corinthians 13:12).