Verily, verily, I say unto you, He that enters not by the door into the sheepfold, but climbs up some other way, the same is a thief and a robber.
All Commentaries on John 10:1 Go To John 10
Theophilus of Antioch
AD 184
Or, the Holy Spirit is the porter, by whom the Scriptures are unlocked, and reveal the truth to us.
He alludes to Antichrist, who shall deceive for a time, but lose all his followers when he dies.