Perhaps without knowing it, Trump had stepped into one of Christianity’s oldest fault lines: faith versus works.

Protestants like the evangelicals on Trump’s board stand firmly on the “faith” side. No amount of good deeds will save your soul, they say, if you don’t assent to the proper Christian beliefs. Catholics and other Christians mostly agree, but also say that faith without works is dead.

Even some evangelicals now say the pendulum has swung too far in the “faith” direction, with many Americans claiming to be Christians while refusing to demonstrate Christian behavior.

In the new book “You Are What You Love: The Spiritual Power of Habit,” James K.A. Smith, a Christian philosopher, tries to rescue the ancient notion that we are defined by our daily dispositions, routines and disciplines. Rather than sequester “religion” as something we do on Sunday, Smith argues that our habits — he calls them “liturgies” — form “grooves in our soul.”