This week's question-box question is a two-fer: What is a patron saint? What is a saint? Who is your favorite? and also I've noticed that when Matt [the other Catechist] invokes the saints during the litany of saints, he often invokes 'Saint Michael the Archangel.' How can an angel be a saint?

A saint is basically anybody who lives happily for eternity with God in heaven. The Baltimore Catechism # 1 (and 2) question 6 asks, "Why did God make you?" It answers by saying that "God made me to know Him, to love Him, and to serve Him in this world, and to be happy with Him forever in the next." Thus, it is proper to say that our purpose in life is to become saints, and that the purpose of the Church is to help us to do this.

A part of the way which the Church does this for us is to point to certain people who have gone on before us in the faith. These people have lived holy* and virtuous lives, and so are held up to us as "role-models" in the faith. In his First Letter to the Corinthians, Saint Paul advises them (and us) to "Take me as your example, just as I have taken Christ for mine" (1 Corinthians 11:1). The Church is therefore following the apostle's advice and holding up the lives of her holy men and women for us to take as "examples" of how to "live in Christ."

Thus, some of those who are in heaven now are revealed to the Church as "good examples". These people are the beatified or canonized saints: the people who we call "Blessed" or "Saint" (respectively). Thus, we have Blessed John Paul II, Blessed John Henry Cardinal Newman, or Blessed Duns Scotus; or Saint Dominic, Saint Paul, Saint Martha, Saint Mary Magdalene, etc. These people show us the many ways of living a holy and Christ-filled life which we might learn from and imitate.

Besides being good role-models, the saints are our intercessors (1 Timothy 2:1-4). They are the "cloud of witnesses" (Hebrews 12:1), and the righteous whose prayer "has great power in its effects" (James 5:16). We can in principle ask any one of the saints to pray for us—as we do in our litany at the end of each RCIA session—and some of the saints have additionally become attached to particular causes. For example, Saint Anthony (of Padua) is the patron saint of lost items. Next time you lose your car keys, ask for Saint Anthony's intercession. Or next time you have a sore throat, you might petition Saint Blaise, and Saint Theresa if you have a headache. It may also be worth developing a relationship with one or two "personal" patrons: especially since at some point you will get to pick a confirmation saint.

For what it's worth, mine is Saint James the Greater, in part because my first name is James and in part because he is one of my favorites: the first apostle to be martyred, one of Jesus "inner circle" of apostles, and sometimes symbolizing the virtue of hope. Plus, he's depicted holding a sword, because he was beheaded. Some of my other favorites are Saint Dominic—founder of my order!—Saint Thomas Aquinas (the greatest Philosopher ever), Saint Albert the Great (patron of scientists), Pope Saint Pius V (who arranged the Holy League for the Battle of Lepanto and also issued the Catechism of Trent) and Saint Athanasius (who stood against the world for the Faith). My wife, on the other hand, prefer St Therese of Liseux, St Rafqa (a Marionite!), St Cecilia, and St Hildegard von Bingen.

As for Saint Michael the Archangel, we can call him a saint, too, because he is a holy person (in this case, and angel not a human) who is enjoying the happiness of heaven with God. We refer to him by name, because we know his name (it has been revealed to us). The other two known holy angels are saints Gabriel (who we meet in the book of Daniel and then again at the beginning of St Luke's Gospel) and Saint Rafael (whom we meet in the book of Tobit). Saint Michael is mentioned by name in the books of Daniel, Jude, and Revelation.

--Footnote--
*Holy: in latin, this comes from sanctus, from which word we also get "Saint." Thus, when we say "Saint Michael the Archangel" we are also saying "Holy Michael the Archangel". This is thus another way of answering that second question.