Complex sentence: Culkin was raised Roman Catholic; he attended a Catholic school (St. Joseph's School of Yorkville) for five years before moving on to Professional Children's School; he also studied ballet at the School of American Ballet.
Split into simpler sentences: Culkin was raised Roman Catholic; he attended a Catholic school (St. Joseph's School of Yorkville) for five years before moving on to Professional Children's School. He also studied ballet at the School of American Ballet.