An on-going debate in the Medieval world was over the relationship between outer grace and inner virtue.
Some argued that cultivated behavior could nurture inner virtue. A near modern equivalent might the notion, “Act your way into a new way of feeling.”
The difficulty with this approach, of course, is that for it to work there needs to be a fundamental commitment to interior transformation. There also needs to be some measure of interior virtue for it to work. Disciplined or committed people, for example, may transform their lives by beginning with outward action. People who are neither disciplined nor committed, or whose virtue is subverted by depression or guilt will often talk about such changes, but it is difficult for them to ever turn the corner. And, of course, there is another category of human being who acts the part in order to win followers or widen their influence who never intended to cultivate virtue at all.
Other Medieval thinkers argued that genuine transformation is an inside job. Only a commitment to the cultivation of virtue can lead to outward transformation. The gracious human being can be counted upon to act graciously in a way that the person who is apparently gracious cannot.
It is not enough to claim inner virtue, of course. Inner virtue has to be given outward expression. But, of the two, it is the inside job that proves indispensible. In that sense, the cultivation of virtue is a spiritual enterprise. We can’t (as some motivational experts argue) look into the mirror and say, “Everyday you are getting better and better in every way” and have it happen.
Instead we need to listen attentively for the movement of the Spirit in our lives — movement that shapes our motivations, our way of being in the world, our values and passions. When that happens, then, as Paul put it, the Spirit yields fruit, fruit that is (by any other name) a list of virtues: love, joy, peace, longsuffering, gentleness, goodness, faith, meekness and temperance.
It is moving from that inside job to a life shaped by those virtues that we become the children of God.