One of the biggest non-issues that I see in Catholic/Protestant debate is the labeling of Mary as the "Mother of God."
As far as I can tell, Catholics and Protestants hold nearly the exact same view on this subject, they just differ in the terms they use to describe it.
"Jesus is fully man and fully God; Mary gave birth to Jesus (she is his mother); Mary is the mother of God."
No Catholic believes that Mary existed before Jesus. I don't understand the debate.
Biblewonk Alert.
One of the most serious RC errors is their worship of a Mary totally foreign to the bible except under the name of "the Queen of Heaven" or "Diana".