 He was present at the First Council of Ephesus in 431 With all his zeal, he could not prevent the progress of the Arian heresy which the Goths were spreading abroad; there is evidence that an Arian rival bishop was established in Narbonne.The siege of Narbonne by the Goths in 436 and dissensions among the Catholics so disheartened him that he wrote to Pope Leo I, renouncing the bishopric, but St. Leo dissuaded him ("Epistle" CLXVII).Rusticus then endeavored to consolidate the Catholics.