I want to thank Matt Smethurst over at The Gospel Coalition for posting my interview on the NT Canon with Mark Mellinger. I gave this interview back in April when I was at the TGC national conference participating on a panel discussion on the authority of Scripture (for that discussion, see here).
The four Gospels were supposedly written in the first century, but no NT document is extant from the first century. So, how do we know that they were written in the first century? (I believe the Canon).