The Gospel that Allah (S.W.) revealed to Jesus (PBUH) is not necessarily the chapters of the New Testament, which Christians consider holy, and was written by Jesus' (PBUH) disciples and those after them. These human stories, biographies, and letters are not the revelation that Allah (S.W.) had revealed to Jesus (PBUH).
How could people attribute their own writings to Allah (S.W.) falsely?
"Then woe to those who write the Book with their own hands and then say, 'This is from Allâh,' to purchase with it a little price! Woe to them for what their hands have written and woe to them for that they earn thereby." (Al- Baqarah: 79)
This verse is clear divine evidence that the people of the book (Jews and Christians) had altered and changed the word of God. It declares that what they have now, Old and New Testaments is not the word of Allah (S.W.).