By “messenger of
Satan” Paul means the insults, attacks and riots which he had to face.
(Theodoret of Cyrus, "Commentary on the Second Epistle to the Corinthians
349," PG 82:450, in 1-2 Corinthians, ed. Gerald Lewis Bray [Ancient
Christian Commentary on Scripture; Downers Grove, Ill.: InterVarsity Press,
1999], 305)
