Galatians 3:7

γινώσκετε ἄρα, “ye perceive then.” γιν., almost certainly indicative, for the imperative never occurs in the N.T. with ἄρα, and only once with ἄρα οὖν, 2 Thessalonians 2:15; cf. 1 Thessalonians 5:6.They could perceive the following truth of the all-importance of faith, and their consequent relation to Abraham, from the preceding argument clinched by Galatians 3:6.

ὅτι οἱ ἐκ πίστεως. Probably this phrase = those who take their start in religion from faith (cf. οἱ ἐξ ἐριθίας, Romans 2:8), according to the tenor of the preceding verses. Thus it is not the opposite of οἱ ἐκ περιτομῆς, which seems always to mean men of Jewish origin by birth, Galatians 2:12; Acts 10:45; Acts 11:2; Romans 4:12; Colossians 4:11, and οἱ ἐκ τῆς π., Titus 1:10[91]. Its true antitheses are οἱ ἐκ νόμου, Romans 4:14; Romans cf.16[92] (not οἱ ὑπὸ νόμον, infra Galatians 4:5; 1 Corinthians 9:20 bis, which = observant Jews) and ὅσοι ἐξ ἔργων νόμου εἰσίν, Galatians 3:10[93]. There is no need to understand υἱοὶ ὄντες (Rendall) or δικαιωθέντες (Ramsay). Observe that οἱ διὰ πίστεως does not occur. St Paul’s thought goes deeper than to the means. Faith is the human source, though the Divine means.

[91] Is affixed to a word it means that all the passages are mentioned where that word occurs in the New Testament.
[92] Is affixed to a word it means that all the passages are mentioned where that word occurs in the New Testament.
[93] Is affixed to a word it means that all the passages are mentioned where that word occurs in the New Testament.

οὖτοι, Romans 8:14; James 1:25.

υἱοί εἰσιν Ἀβραάμ. The Jews claimed spiritual, because physical, relationship, Matthew 3:9 (|| Luke 3:8); John 8:33; John 8:37; John 8:39. Observe not τέκνα but υἱοί, i.e. sonship with its full privileges. See Appendix, note C, for a brief consideration of Ramsay’s theory that this passage suggests acquaintance with the Greek (not Roman) law of sonship and inheritance, and so favours the South Galatian theory.