31. διό. Always of practical result rather than argumentative inference (οὖν); a deduction from the preceding Gal 4:21-30, which must be carried out in daily life (thus forming the transition to the next section); we are therefore free.
ἀδελφοί. Once more, see Gal 4:28 note.
παιδίσκης, “a mere bondmaid.”
τῆς ἐλευθέρας. The absence of the article before παιδίσκης, and its insertion here, rhetorically direct attention (see Milligan on 1Th 4:8) and also suggest the unique character of the Jerusalem above, cf. Gal 1:10 (τὸν θεόν). This is our true and proper position, to be and behave as—children of the free!