[Ali Imran]

I will tell you one reason why it cannot be Muhammad...because Allah did not ask you to believe in the NT ...it is not one of Allah's revealed books 

If you believe that Muhammad fits the description of the one to come after Jesus... then you are submitting to the truth of the NT ...I hereby proclaim you as a Kafir once again 

I never said I submit to the NT. I only submit to the one true God.

And yes, the NT is not a revelation. But, does it contain some truth? Yes. How do I know? Because the Quran is our supreme authority and if the information in the NT matches the Quran, we can say it is true. 

If I see a poster on the wall of Harvard university and it has a statement that matches what is in the Quran, I will say that statement in that poster is true, even though the poster is not a revelation from God.