Since we just started the year of faith, I'd like to consider how faith is a virtue. As a virtue, it helps us become holy. St. Thomas begins with faith when he writes about the virtues in the Summa Theologiae. His moral teaching is so positive because he centers it around virtue, not sin (though he certainly deals with sin as well).
Faith is the foundation of all the other virtues. It's given as a gift with baptism, and once we are baptized we can never lose it--unless we commit a sin directly against faith. Even if a person commits other serious (mortal) sins and loses the life of sanctifying grace, the virtue of faith remains (along with hope). However, without grace it's not a living faith. But we still need it, because it enables us to come back to God. If we lost faith with every sin, how could we ever repent?
It seems to me that people don't think about faith as a virtue. Today, it seems that even many Catholics regard faith as something we do. In other words, that it's up to us to decide whether or not we will believe, what we will believe, etc. Since we're living in an age of relativism, it's easy to lose our bearings. But faith keeps us moored in Christ. Faith is a gift of God and is based on God himself.
An enriched understanding of faith as a virtue can revitalize our faith. So I'm hoping to do some posts on what St. Thomas teaches about faith precisely as a virtue, and what that means in our everyday life.