250.
That St.John wrote his Gospel with a view to confute Cerinthus, among other false teachers, is attested first by Irenaeus, who was a disciple of Polycarp, and who flourished within less than a century of St.John's time.
I have little trust and no faith in the gossip and hearsay-anecdotes of the early Fathers, Irenaeus not excepted.

"Within less than a century of St.John's time." Alas! a century in the paucity of writers and of men of education in the age succeeding the Apostolic, must be reckoned more than equal to five centuries since the use of printing.

Suppose, however, the truth of the Irenaean tradition;--that the Creed of Cerinthus was what Irenaeus states it to have been; and that John, at the instance of the Asiatic Bishops, wrote his Gospel as an antidote to the Cerinthian heresy;--does there not thence arise, in his utter silence, an almost overwhelming argument against the Apostolicity of the 'Christopaedia', both that prefixed to Luke, and that concorporated with Matthew?
Ib.p.

257.
'In him was life, and the life was the light of men'.

The same Word was life, the [Greek: logos and zoae], both one.