Now as is the seed of the Word, so also the fruit that comes forth of it, and the fruit declares the seed. If men are ungodly, it is proof that they have a falsified gospel, have heard an anti-Christian teacher and accordingly are deceived. But if holy and godly and just and conform to the example and likeness of Jesus Christ Who came for that purpose, it is proof that they have heard and believed the true gospel.
We have now to look upon and take into consideration not the populace or most people, for they are always on the broad way to destruction and only few are on the narrow way to life everlasting. So today, all around us, the world is full of anti-Christians. True Christians who conform to Christ and who follow Him in mind and life as children of God reborn of the seed of His word are indeed scarce and they are afraid to accept anything new, i.e. anything that the spirit of anti-Christ (the lie) has taught and propagated in the world since the apostles' time.
Even in his time, by saying that "many deceivers are entered into the world," John meant neither the Jews nor the Greeks (for they confess not as and for themselves Jesus Christ come in the flesh). John came to know in the church of Christ itself the nature or character of false teachers who practised deception with the gospel.
--S.H. Froehlich
Excerpt: Epistles of John Volume IV