I have been challenged by a Catholic to prove several things from scripture alone From scripture alone how do we know that Matthew wrote the Gospel of Matthew and that Mark, Luke and John wrote their Gospels? Also how do we know that Luke wrote Acts and it is inspired scripture? From Scripture alone who was Mark and Luke? They clearly were not apostles so why do we consider them as being inspired authors? None of the 27 books claim to be the inspired word of God so why do we believe they are inspired from scripture alone. From scripture alone why is the book of Hebrews in the bible, who wrote it and why is it considered inspired? Scripture never says how many books should be in the New Testament. From scripture alone why are there only 27 books and not more or less? I can't answer these questions using scripture alone. How can I respond?