Does Doctrinal Diversity Lead to Doctrinal Indifference?

“The goal that diversity in secondary matters would be welcomed quite soon passed over into an attitude that evangelicalism could in fact be reduced simply to its core principles of Scripture and Christ. In hindsight, it is now rather clear that the toleration of diversity slowly became an indifference toward much of the fabric of belief that makes up the Christian faith.”

– David Wells, The Courage to be Protestant, 8.

Does doctrinal diversity on secondary issues necessarily lead to doctrinal indifference? If not, what keeps it from sliding into indifference?