The correct answer is religious tolerance
Enlightenment authors believed that religious tolerance would produce not only mutual indulgence but also religious concord. Toleration was used as a way to achieve the desired unity. Locke for example easily combined concord, toleration, and exclusion. He trusted that toleration is a ladder that would lay the foundations of liberty and peace. He said: “Men will always differ on religious questions and rival parties will continue to quarrel and wage war on each other unless the establishment of equal liberty for all provides a bond of mutual charity by which all may be brought together into one body.”