Romans 14:20

κατάλυε τὸ ἔργον τοῦ θεοῦ. The οἰκ., the duty of Christian to Christian, is GOD’s own work; cf. 1 Corinthians 3:9; Acts 20:32. καταλ. is suggested by the metaphor of building; cf. Mark 15:29; Galatians 2:18; 2 Corinthians 13:10.

πάντα μὲν καθαρά. The admission of Romans 14:14 is repeated, to bring out more explicitly the harm which may be done by insisting on rights; 1 Corinthians 10:23; 1 Corinthians 8:9.

ἀλλὰ κακὸν, sc. your use of this principle, τὸ τῇ ἐξουσίᾳ χρῆσθαι. The assumption, as throughout, is that the weak brother may be led to act against his conscience by the example of the strong.

διὰ προσκόμματος. Under conditions which will make him fall. διὰ w. gen. expresses the conditions of an action; cf. Romans 2:27; Romans 8:25; 2 Corinthians 2:4; Blass, p. 132 f.