From the top of my head, my first answer would be: The more your faith changes you on a fundamental level, the more it becomes part of your personality -- while at the same time the least visible at the surface, the better.
Christ said when you pray, do it in your room, not in the open, for other people to see. This general idea nails it, IMO. Ideally, your faith should impact you in a manner that makes other people recognize you as an example of goodness to emulate, even when they have no clue what your religious views are.
You can pray all day, go to church at every occassion, talk about your faith whenever you can, make a lot of fuss about yet -- yet still not be truly affected by it in your heart. Likewise, the opposite can be true, too.
But what really matters is the change of heart.
