Complex sentence: The Puritans, then known in England as the "Geneva Church," for John Calvin's reforms, were advocating the demotion of clergy and ecclesiasticism, and Hooker attempts to work out which methods of organizing churches are best.
Split into simpler sentences: The Puritans, then known in England as the "Geneva Church," for John Calvin's influence on them, advocated the demotion of clergy and ecclesiasticism. Hooker attempted to work out which methods of organizing churches are best.