4:21  Paul’s tone changes somewhat at this point, turning from a personal appeal back to an argument from Scripture (cf. 3:6–9) and to teaching what he and the Galatian believers already have in Christ. Paul begins with a direct address, Tell me, you who want to be under the law. The wording of the question critiques their desire, for Paul presents the law as something under which people are held.

The passage beginning in this verse and extending to 5:1 works with several themes that have already been introduced: giving birth (3:19), slavery (3:8), freedom (3:25), Abraham (3:6–8, 16–18, 29), the promise (3:14, 18, 21–22, 29), sonship (4:5–7), a covenant (cf. 3:15), persecution of believers in Christ by Jews (1:13), and inheritance (3:18; 4:1–7).

Themes and features from Genesis 21 appear in …