He was known for both his political and his theological activities. In 1914, he would be arrested by the Tsarist government for his activities with the Austro-Hungarian government during World War I. After his release in 1917, he would speak in defense of an independent Ukrainian national state and would support the establishment of the Western Ukrainian National Republic. He would be confined to Lviv for his support of the Ukrainian National Rada by the Polish government. In 1931, he established the Ukrainian Catholic Union in order to further the Church's social teaching and enhance its standing in Ukraine. He would be denounced by pro-Soviet Ukrainians for his criticism of the Ukrainian famine of 1932-1933 and his condemnation of the Communist government.
When the Nazis invaded the Soviet Union, Sheptytsky encouraged obedience to the new occupying state. However, when he realized their persecution of the Jews, he was at the forefront of the Church leaders to defend them. His mistake was one that was made by the Russian Liberation Army, for those familiar with The Gulag Archipelago by Aleksandr Solzhenitsyn. Many believed the Nazi government would promise more freedom than the Soviets had, for when one only lives under a totalitarian regime, it is easy to fail to distinguish or discriminate the fact that no totalitarianism is better than another.
Sheptytsky was a learned man, well-regarded for his pastoral and theological discipline. He was an intellectual, a politician, and a Churchman. He aided Pope Pius X in the establishment of the Russian-Greek Catholic Church. The move met with little success as very few became adherents to the new church and it was heavily opposed by the Ukrainian Orthodox, yet Sheptytsky's vision for an Uniate Church in Russia would not be dissuaded so easily. He met many learned philosophers, theologians, and Catholics when he visited the Russian Empire in the late 19th century, including Vladimir Soloviev. His title of Bishop of Komianets-Podilskyi, though an inactive eparchy, gave him full responsibility of all the Eastern Rite Catholics throughout the Russian Empire. It was the Petersburg Synod of Eastern Catholics in 1917-1918 that reversed much of the damage of the Synod of Zamość. The Petersburg Synod also approved the veneration of canonized Orthodox saints in the Eastern Catholic Church. Of course, certain saints who had died in schismatic churches were already venerated such as St. John the Almsgiver, St. Elesbaan, the King of Ethiopia, and St. Isaac of Nineveh.
Sheptytsky wanted to unite all of Ukraine under a united Ukrainian Church. His vision was to establish a Ukrainian Church under the authority of the Pope of Rome. He was heavily Eastern and sought the restoration of Eastern traditions, but he was always a fierce Papist. The Ukrainian Orthodox hated this idea for they would never want an autocephalous church underneath the authority of the Pope of Rome. Sheptytsky was an Hebraist and was well-studied in the Hebrew language. This helped him gain Jewish allies when the Nazi persecutions began. He kept Jews in hiding in the monasteries and instructed his flock to do the same. His brilliance and resilience under persecution earned the respect of the Church and when the Soviets took the Ukraine again, the persecutions of the Church would remain moderate. He stayed in Lviv until his death in 1944.
Many of his works have been published posthumously. The Sheptytsky Institute under the University of St. Michael's College in the University of Toronto is named after him. He had visited Canada in 1912. His disciple, Met. Josyf Slipyj, he consecrated, and was made a Cardinal by Pope Paul VI. Some of his works were published in volumes such as The Works of the Servant of God Metropolitan Andrei Sheptytsky: Pastoral Letters and The Church and Church Unity: Documents and Materials. He wrote much on topics such as ecumenism, theology, spirituality, history, and philosophy. His vision for an Uniate Church under the full authority of the Pope of Rome would be betrayed at Vatican II when the hierarchy broke for a false ecumenism favoring the Eastern Orthodox Church's role as opposed to the Traditionalist Catholic position, and the Catholic position, of the Church's jurisdictional authority being fully placed under the Pope of Rome. Sheptytsky was nevertheless influential for Eastern Rite Catholics and Ukrainian-Greek Catholics in recovering much of the Eastern Tradition that had been lost and forming us once again back to the Catholic theology of the one Mother Church. We are not Orthodox in Union with Rome. We are Greek Catholics and our theology is Catholic. Met. Andrei Sheptytsky is venerated on November 1 in the Ukrainian Catholic calendar.
Sources:
Confessor Between East and West, Jaroslav Pelikan