I put up a link on Mary because I think John Newman explains it far better than I can.
My question to you, rather, was "How do you know the rightly inspired books are in the NT since you reject the authority of Rome who put together and approved of said scripture?"
you're avoiding the question ... you're trying to ascribe 100% infallability when this teaching is clearly wrong to anyone who has read the Bible ...
now Mary is either the "mother of God" or she isn't ... I'd be interested if you'd be willing to make public your stance on this issue ...