1 John 4:1-3
Beloved, do not believe every spirit
[speaking through a self-proclaimed prophet];
instead test the spirits
to see whether they are from God,
because many false prophets and teachers
have gone out into the world.
2 By this you know and recognize
the Spirit of God:
that acknowledges and confesses
[the fact] that
Jesus Christ has [actually] come in the flesh
[as a man]
is from God
[God is its source];
3 and every spirit
that does not confess Jesus
that He has come in the flesh,
but would deny any of the Son’s true nature]
is not of God;
this is the spirit of the antichrist,
which you have heard is coming,
and is now already in the world.
Galatians 1:8, 9
8 But even if we, or an angel from heaven, should preach to you a gospel contrary to that which we [originally] preached to you, let him be condemned to destruction!
9 As we have said before, so I now say again, if anyone is preaching to you a gospel different from that which you received [from us], let him be condemned to destruction!
2 John 10
If anyone comes to you and does not bring this teaching [but diminishes or adds to the doctrine of Christ], do not receive or welcome him into your house, and do not give him a greeting or any encouragement;