‘This is the disciple who bears witness of these things and wrote these things, and we know that his testimony is true.'
These words are the equivalent of a witness's signature. A group of important Christians confirm that the Gospel was written by the beloved disciple, who was still alive and bearing witness, and that they had good reason to know that it was true. This verification may suggest that other less reliable writings had begun to circulate around the turn of the century so that verification had now become important. Thus on completing his book John asked his fellow-elders to subscribe their testimony.