THE PROPHET ISAIAH IS ONE OF MANY whom God sent to correct changes made by men to His Word, as It had been given to mankind through the Holy Spirit, and Chapter 1 of the Book of Isaiah provides absolute proof apostle to the Gentiles -- Paul, preached doctrine in Jesus' Name that Jesus did not preach.
Reference Links Below:
Additional Biblical info - http://dld.bz/Cymh;
OT Proves Crucial Doctrine Jesus Preached Not In NT - http://dld.bz/bS94j;
Gospel of the Holy Twelve - http://dld.bz/bZmUA;
The Clementine Homilies - http://dld.bz/bZmUT;
Apostle to the Gentiles, Paul - http://dld.bz/aCafB;
Roman Emperor Constantine & First Council of Nicaea 325 AD - http://dld.bz/aBMVK