Immanuel = “God with us”
The Greek word for *Lord* is not *Theou* (God) but *Kyriou* (Lord)
That verse in Luke proves nothing to support that Elizabeth means *God* when she says *Lord* because she never used the word for God.
I was just thinking the other day in response to some articles on this subject that the Catholic charge against Bible-believing Protestants makes no sense. We DO believe Mary is “the mother of God” in the sense that we believe that Jesus was and is God. We aren’t Jehovah’s Witnesses, for example. Jesus was and is God, and Mary is His mother. Through her, God entered the world in human form. We agree with all that, and that’s one of the things we actually agree on in a formal sense.
And interestingly, too, Wikipedia says that “Theotokos” means something like “the one who gives birth to God,” rather than “Mother of God.” To that, Catholics would say, “mother” means “one who gives birth to.” Yet, the word “mother” isn’t used. So why should they have trouble with Protestants saying to them that Mary is the mother of Jesus, or the Christ? After all, even if the word God isn’t used, we believe Jesus Christ is God, so it is implicit in the belief that Mary is the mother of Jesus Christ, and hence, God - so long as someone believes that Jesus was and is God.
And then, furthermore, they say they believe just as we do - that Mary isn’t the mother of the eternal God. That isn’t what they mean by “Mother of God.” They mean that she is the mother of the Son of God in His Incarnation.
A lot of the controversy seems to involve the difficult nature of the Trinity, because the essential stated beliefs are the same.
The problem I believe we have as Protestants is that despite what Catholics say, in practice they treat Mary as God in many respects.