1 John 4:1-6

1 John 4:1-6
Dear friends, do not believe every spirit, but test the spirits to see whether they are from God, because many false prophets have gone out into the world. ² This is how you can recognize the Spirit of God: Every spirit that acknowledges that Jesus Christ has come in the flesh is from God, ³ but every spirit that does not acknowledge Jesus is not from God. This is the spirit of the antichrist, which you have heard is coming and even now is already in the world.

Just because someone says they are from God does not mean they are from God.  Do they deny the deity of  Christ?  They are not from God.
 
⁴ You, dear children, are from God and have overcome them, because the one who is in you is greater than the one who is in the world. ⁵ They are from the world and therefore speak from the viewpoint of the world, and the world listens to them. ⁶ We are from God, and whoever knows God listens to us; but whoever is not from God does not listen to us. This is how we recognize the Spirit of truth and the spirit of falsehood. 

When we except Christ's payment for our sin, we are sealed with the Holy Spirit.  He lives within us.  What we say and do should be different from the world around us.  What they say and do should be so different that we can immediately recognize it as false.

God Bless.