In 1609 St. Francis de Sales published a book called Introduction to the Devout Life. Unlike some other books (like, for example, The Imitation of Christ, which I love) St. Francis wrote this Introduction for folks like you and me. As Andrew Hanson writes in CCEL’s introduction to the book at the link above:
Do I need to go into full-time ministry to live a truly Christian life? Am I really a Christian if I’m not out preaching the gospel in dangerous places where people have never heard of Christ? Can secular work benefit the kingdom of God? All Christians struggle to discern God’s call on their life, but God does call all to live a Christ-centered life. Introduction to the Devout Life by St. Francis of Sales attempts to help Christians discern what it means to be a child of God in a secular world. We can glorify God in a secular world, and be a testimony to the world of God’s abounding grace and love.
Yes, Virginia, we can and should strive to live devout lives here and now: as butchers, bakers, candlestick makers, overworked system administrators, salesmen, or whatever we do. We need not be in “full-time ministry” to be devout, and to live fully for God. And this is what St. Francis sets out to teach us in his book.
What I found interesting in the introductory chapter to the book is that St. Francis contradicts (as is usual for Catholic theologians) the false Protestant notion about Catholics that we believe in salvation by works.
To conclude: charity and devotion differ no more one from another than the fire does from the flame; for charity is a spiritual fire which, when inflamed, is called devotion. Hence it appears that devotion adds nothing to the fire of charity, but the flame, which makes it ready, active, and diligent, not only in the observance of the commandments of God, but also in the execution of his heavenly counsels and inspirations. (I.1)
[Note: The CCEL translation linked in the first sentence of this post is not the same translation as the one I quote here from Google books, though it is the same in substance of course. I wanted to use this translation specifically because of its use of the word charity for “love”.]
In Catholic usage, charity is a theological virtue: that means that it is something that God (and only God) can give us. We cannot love God rightly apart from this gift. This fits with what St. Francis says here. Devotion on our part adds nothing to the charity that God sets alight in our hearts; it is merely the flame of that fire. And because of that flame, our souls burn with love for God, and that love for Him finds expression in obeying Him (cf. John 14:15). We are saved by the grace of God, who enables us to love Him. We cannot love Him rightly without His help. In this book St. Francis wants to help us do exactly that.