Angel: I I I IAm the Bird of America, the Bald Eagle,Continental Principality,LUMEN PHOSPHOR FLUOR CANDLE! (2.2.6)
It seems like the angel is saying that she is the spiritual essence, or energy, of America. Based on the other angels we meet later in the play, who all represent large geographic areas, we're guessing she represents all the other countries in North and South America too.
Angel: Open me Prophet. I I I I amThe Book.Read. (2.2.36)
Much like Moses was given the tablets bearing the Ten Commandments, Prior is given a book that's supposed to tell him how human beings ought to behave. Unlike Moses, though, Prior thinks these orders from Heaven are a really bad idea.
Angel: You can't Outrun your Occupation, Jonah. (2.2.104)
Here the angel compares Prior to the biblical prophet Jonah. Like Prior, Jonah disobeyed Heaven's command. In the Bible God tells Jonah to go be a prophet in a city called Nineveh, but Jonah hops on a boat headed the other direction. He ends up being swallowed by a whale (or a big fish) and eventually repents his denial of God. Prior Walter never repents; he stands firm against the will of Heaven.