Whether or not Mary actually sang this song is irrelevant because the early Church did, and what it gives us is great insight into what the Church believed the birth, life, death, and resurrection of Jesus meant for the world. And, we can assume, what it did not mean.
What it meant is:
- God favors the lowly
- God gives mercy to those who fear him - i.e. give him reverence, honor, and respect
- God leaves the proud to be the victims of their own folly
- God makes the powerful weak and the weak strong
- God cares for the poor (and the poor in spirit)
- God keeps his promises
Now, think for a minute about what the Church (not your church, but the Church Universal) says the birth, life, death, and resurrection of Jesus means for the world. Do they sound the same? I doubt it. The Church (at least the part of it that gets press) is usually spouting off about: the end times, homosexuality, your sinfulness, its power position with the power players, etc. To me, this sounds almost exactly the opposite of what Mary (and the early Church) said about God. To me, this sounds like God leaving the proud to be victims of their own folly. To me, it means that preachers need to get about the business of talking about what it means to follow the God that Mary sings about.
It is dangerous and radical and yet no more so than the Son of God being born of a teenage virgin in 1st century Palestine.
Seriously, have you ever read the Magnificat?