In the Book of Tobit, angel Raphael pretends he is Azariah, the son of Hananiah the elder. Why did the Angel lie? Isn’t it a sin to lie?

It is a sin to lie, but the angel isn’t exactly lying. In this situation it’s more like he isn’t revealing the whole truth–at least not yet.

The nature of St. Raphael’s mission required that he keep his angelic identity hidden. Other angels in the Old Testament did this as well. Angels are fearful, powerful, and glorious creatures–that’s why they often begin their messages with “do not be afraid!” Masking their angelic nature serves a practical purpose–and it also emphasizes that God is the one who deserves the glory, not the angel.

The reason St. Raphael gives the name Azariah to Tobit in the first place is because he urges the angel to tell him where he is from.  So Raphael gets around it with a funny trick: he gives Tobit and Tobiah the name “Azariah, son of Hananiah.” The name Azariah means “God has helped” and Hananiah means “God has shown mercy.” So basically Raphael is disguising his identity while at the same time secretly hinting at it–his whole mission, as revealed at the end of the story, began because Raphael brought their family’s prayer before the Lord and so was sent to help them (see Tobit 12:11-20). He calls himself a “kinsman” and an “Israelite” as a way of showing that they belong to the same spiritual family–the people of God.

So you can sort of think of Azariah as the angel’s “codename” for the mission!

And just to clear up any confusion on lying, the Catechism notes that “the right to the communication of the truth is not unconditional” (CCC 2488). We have to judge in particular situations whether it is the right time and circumstance to reveal the truth. Being truthful requires prudence, too. Also, “no one is bound to reveal the truth to someone who does not have the right to know it” (CCC 2489). In the case of St. Raphael, Tobit and his family didn’t have the right to know his true identity–but in the end, he reveals it to them to “declare the works of God with due honor” (Tobit 12:11).The irony in the story of Tobit is that when St. Raphael first enters Tobit’s house and greets him, he tells him: “Take courage! God’s healing is near; so take courage” (Tobit 5:10). What does the name Raphael mean? “God’s healing” (or “God heals”)!