Task: Question Generation
Input (English): Pope Julius had died in April, 352, and was succeeded by Liberius. For two years Liberius had been favourable to the cause of Athanasius; but driven at last into exile, he was induced to sign an ambiguous formula, from which the great Nicene text, the "homoousion", had been studiously omitted. In 355 a council was held at Milan, where in spite of the vigorous opposition of a handful of loyal prelates among the Western bishops, a fourth condemnation of Athanasius was announced to the world. With his friends scattered, the saintly Hosius in exile, and Pope Liberius denounced as acquiescing in Arian formularies, Athanasius could hardly hope to escape. On the night of 8 February, 356, while engaged in services in the Church of St. Thomas, a band of armed men burst in to secure his arrest. It was the beginning of his third exile.
Output (English): What was  Athanasius doing when he was arrested?