Complex sentence: Saint Clement's was not originally founded as an Anglo-Catholic parish, but beginning with the 1869 arrival of Hermon Griswold Batterson, a priest of the Society of the Holy Cross, the parish was increasingly influenced by the theology of the Oxford Movement.
Split into simpler sentences: Saint Clement's was not originally founded as an Anglo-Catholic parish. It was not until the 1869 arrival of Fr. Hermon Griswold Batterson, a priest of the Society of the Holy Cross, that the parish increasingly came to be influenced by the theology of the Oxford Movement.