That this Epistle is really by the same author as the Gospel is not indeed absolutely undoubted, but I imagine that it is as certain as any fact of literature can be.
The evidence of style and diction is overwhelming [Endnote 277:1].
We may set side by side the two passages which are thought to be parallel.
_Ep.

ad Phil_.c.

vii.
[Greek: Pas gar hos an mae homologae Iaesoun Christon en sarki elaeluthenai antichristos esti; kai hos an mae homologae to marturion tou staurou ek tou diabolou esti; kai hos an methodeuae ta logia tou Kuriou pros tas idias epithumias, kai legae maete anastasin maete krisin einai, outos prototokos esti tou Satana.] 1 _John_ vi.

2, 3.
[Greek: Pan pneuma ho homologei Iaesoun Christon en sarki elaeluthota ek tou Theou estin.

Kai pan pneuma ho mae homologei tou Iaesoun ek tou Theou ouk estin, kai touto estin to tou antichristou, k.t.l.] This is precisely one of those passages where at a superficial glance we are inclined to think that there is no parallel, but where a deeper consideration tends to convince us of the opposite.
The suggestion of Dr.Scholten cannot indeed be quite excluded, that both writers I have adopted a formula in use in the early Church against various heretics' [Endnote 277:2].