Paul typically includes a thanksgiving after the opening greeting (Romans 1:8–15; 1 Corinthians 1:4–9; Philippians 1:3–11; Colossians 1:3–8; 1 Thessalonians 1:2–10; 2 Thessalonians 1:3–10; 1 Timothy 1:12–17; 2 Timothy 1:3–7; Philemon 1:4–7). In Galatians, however, such a thanksgiving only comes later (Galatians 3:3; Galatians 4:12–15; Galatians 5:7)1 and instead there is an expression of astonishment.2
Galatians 1:1 – 2:21 can be further subdivided as follows:3
Greeting: Paul’s apostolic authority (Galatians 1:1–5)
Problem explained: Desertion from the gospel (Galatians 1:6–10)
Paul’s gospel derived from God, not from people (Galatians 1:11 – 2:21)
6 I am astonished that you are so quickly deserting him who called you in the grace of Christ and are turning to a different gospel