1 John 4:1 – 2
English Standard Version (ESV)
4
Test the Spirits
1 Beloved, do not believe every spirit, but test the spirits to see whether they are from God, for many false prophets have gone out into the world. 2 By this you know the Spirit of God: every spirit that confesses that Jesus Christ has come in the flesh is from God,
From BibleGateway.com: http://www.biblegateway.com/passage/?search=1+john+4.1-2&version=ESV