Complex sentence: In 1966 he became the first president of that seminary, and remained so until 1984, when he became the theologian-in-residence of Trinity Presbyterian Church (part of the Presbyterian Church in America) in Charlottesville, VA.
Split into simpler sentences: In 1966 he became the first president of that seminary, and remained so until 1984. At that point he became the theologian-in-residence of Trinity Presbyterian Church (PCA) in Charlottesville, VA.