2 John 1:1-4; 2 John 1:6-7; 2 John 1:9

1 The elder unto the elect lady and her children, whom I love in the truth; and not I only, but also all they that have known the truth; 2 For the truth's sake, which dwelleth in us, and shall be with us for ever. 3 Grace be with you, mercy, and peace, from God the Father, and from the Lord Jesus Christ, the Son of the Father, in truth and love. 4 I rejoiced greatly that I found of thy children walking in truth, as we have received a commandment from the Father.
6 And this is love, that we walk after his commandments. This is the commandment, That, as ye have heard from the beginning, ye should walk in it. 7 For many deceivers are entered into the world, who confess not that Jesus Christ is come in the flesh. This is a deceiver and an antichrist.
9 Whosoever transgresseth , and abideth not in the doctrine of Christ, hath not God. He that abideth in the doctrine of Christ, he hath both the Father and the Son.