Tolerance in its conception took on the cast of a virtue because of its concern for the common good and its respect for people as persons. We endure particular customs, behaviors or habits—sometimes even (relatively) bad habits—of people in the interest of preserving a greater unity. In the Lockean context, tolerance was advocated for religious non-conformists. Never was it construed, however, to imply—much less sanction—morally questionable behavior. Consider, however, the devolution of a concept. What was a public virtue in its prior state becomes a vice if and when it ceases to care for truth, ignores the common good, and disdains the values that uphold a community. The culture of ‘tolerance’ in which we presently find ourselves is a culture in which people believe nothing, possess no clear concept of right and wrong, and are remarkably indifferent to this precarious state of affairs. As a result this transmutation of ‘tolerance’ becomes indistinguishable from an intractably intolerant relativism.
J. Daryl Charles, ‘Truth, Tolerance, and Christian Conviction: Reflections on a Perennial Question—a Review Essay," Christian Scholar’s Review 36 (2007): 212 in D. A. Carson, The Intolerance of Tolerance (Grand Rapids: Eerdmans, 2012), 75.