The term mother of God, or more precisely, theotokos, which means God-bearer, was conferred on Mary to elevate Jesus as God and Man. The alternative view was—and is— Jesus as a super prophet, but not a divine being.
Recognizing that Jesus was God incarnate, the Man-Messiah, fully human/fully God, hypostatic union of the theanthropic person, has little to do with the Roman errors that detract from the real Gospel. Venerating Mary (to the point of idolatry), sacerdotalism, indulgences, purgatory, absolution, and all of the other baggage profferred by Rome simply attempts to obscure salvation by grace, through faith, and that not of yourselves, it is the gift of God, not of works, lest any one boast. Sound familiar?
Jesus was not born as a human for the role of a God...He was as you say a prophet, a preacher, a priest and a human...Elizabeth did NOT say the mother of God...She said the mother of my Lord...
Mary was not, is not and never will be the mother of God...
Anyone who knows the bible already knows that Jesus was God and man...No one needs to invent a word to add to it to let us know that Jesus was God and man...Especially while adding the word gives a false notion that Mary was God's mother...
We already know that Mary was Jesus' mother and we already know that Jesus is God...And yet we know that Mary was not the mother of God...God was not created in Mary's womb...The 2nd part of the Trinity was not created in Mary's womb...He already WAS...