Complex sentence: Quoting evidence from sixteenth and seventeenth century historians, he demonstrates the "religious wars" of the Late Middle Ages were not primarily caused by religious intolerance by showing that participants and motives for those wars crossed religious boundary lines.
Split into simpler sentences: Quoting evidence from sixteenth and seventeenth century historians, he effectively demonstrates the "religious wars" of the Late Middle Ages were not primarily caused by religious intolerance. Participants and motives for those wars crossed religious boundary lines.