See my answer to Editor Surveyor.
Orthodox Christianity both Catholic and Protestant believe that Jesus Christ is one person with two natures. This is known as the Hypostatic Union.
http://www.desiringgod.org/blog/posts/what-is-the-hypostatic-union
I think the above site is named after John Piper’s book. So I’ll assume it is vetted by Protestants.
Then what is Nestorian heresy?