Pelagius — on Rom 1:1 (PELAGIUS'S COMMENTARY ON ROMANS)

“Do we wonder why he writes Paul, given that he was called Saul before? Doubtless he did this following the habit of the saints. When they advanced in virtue they were addressed with a different name, so that they might be new people even in name, e.g., Abraham, Sarah and Cephas. … Paul earned the office of an apostle by faithful and matchless service. He was set apart in Acts 13:2. Gospel … means "good news", i.e., of Christ's birth, suffering, resurrection and ascension into heaven.”