Yes, He is the New Covenant.
What writings did He quote when He taught?
People do improperly merge the old and new. They are often people who are trying to find the image of the G-d they want rather than the G-d who is. But you can't divorce the new from the old. All the first Christians, as well as Christ Himself, were Torah observant Jews. Christianity could not have been born in any other setting. G-d called Abraham out of everything he had known so G-d could begin to create the people who would birth the Messiah.
It boils down to where your heart is. Is it proud of what you believe, or is it humble before the majesty of G-d? Scripture tells us G-d loves the latter, and has never had much patience for the former. I have found that the humble tend to interpret the Bible in a very similar manner to each other, which is what first knocked me off my religious high horse.
I'm still learning the humility bit and G-d is being more than patient with me. But as I submit my will to His I am finding that I am becoming more and more a fundamentalist.
Shalom.