This episode provides the answer to the question, demonstrating that Paul's omission of the word "saints" in his intro to the Galatians is best explained by analyzing Paul's letters chronologically. The earliest letters Galatians (49) and 1 and 2 Thessalonians (50 and 51) omit the "word" saints in the intro, though the Thessalonian correspondence uses it in the body of the letters. Paul directed these 3 letters to "churches." 1 and 2 Corinthians, written next (55 and 56), are addressed both to "churches" and "saints." The last 4 letters (Ephesians, Philippians, Colossians, and Romans, written 57-62) are not addressed to churches at all, but just to saints. The best explanation of the omission of the word "saints" in Galatians is therefore stylistic: the omission is consistent with the omissions to the Thessalonians written at the same time and Paul's last 4 letters don't use the word "church" at all in the intro. Paul nevertheless considered the gatherings of saints as "churches," though he chose not to specifically address "churches" in the intro.
