Christianity and “Other” Philosophies — Discerning Boundaries (and When to Cross Them)

A question came to me recently from a reader named Allen:

I am reading some stoic philosophy.  Can we learn from other philosophies or is all we need to know about how to live found in church teaching and our faith? Surely there must be other approaches to daily living that are not incompatible with Christianity but not explicitly talked about in our tra…