What is isnad? Isnad is the chain of narration. The Christians have the matn (text) of their scripture but no isnad (chain of narration). Hence it is impossible to trace back the alleged words attributed to Jesus (peace be upon him) all the way back to his mouth. How can it be known that the Christian material is not mixed with falsehood when there is an absence of isnads and no verification checks in place at all. Hence the believers in the NT are all following utter conjecture and anonymous words whose source we cannot know and neither can we trace back the words or verify them.
Comparing Muslim and Christian scholarship, Bernard Lewis writes:-
"From an early date Muslim scholars recognized the danger of false testimony and hence false doctrine, and developed an elaborate science for criticizing tradition. "Traditional science", as it was called, differed in many respects from modern historical source criticism, and modern scholarship has always disagreed with evaluations of traditional scientists about the authenticity and accuracy of ancient narratives. But their careful scrutiny of the chains of transmission and their meticulous collection and preservation of variants in the transmitted narratives give to medieval Arabic historiography a professionalism and sophistication without precedent in antiquity and without parallel in the contemporary medieval West. By comparison, the historiography of Latin Christendom seems poor and meager, and even the more advanced and complex historiography of Greek Christendom still falls short of the historical literature of Islam in volume, variety and analytical depth." [ Bernard Lewis, Islam in History, 1993, Open Court Publishing, pp.104-105.]
