Those who 'go beyond' it cannot be from God ; 2 John

2 John 1-13
John sent message to the chosen lady and her children.
Because of the truth, which lives in us and will be with us forever.
Grace, mercy and peace from God the Father and from Jesus Christ, the father's Son, will be with us in truth and love.
As you have heard from the beginning, his command is that you walk in love.
Anyone who runs ahead and does not continue in the teaching of Chris does not have God; Whoever continues in the teaching has both the Father and the Son. If anyone comes to you and does not bring this teaching, do not take him into your house or welcome him.
Unlike 1 John, 2 John and 3 John are 'real letters, each long enough to be accommodated on a standard size sheet of papyrus and conforming to the letter-writing pattern of the time.
There is little doubt that 1,2 and 3 John are the work of one author, most like the apostle John or a close disciple of his. The writer calls himself 'the Elder' in both 2 and 3 John. the one addressed to 'the dear lady and her children', the other a private letter, like Paul's letter to Philemon.
2 John, like 1 John, warns against false teacher, encourages the readers to hold to the truth, and focuses on a favorite theme: Jesus command that those who follow him should love one another.
To love others as Jesus loves us means keeping God's commands. For Christians, love and truth go hand in hand.
Why?
Christ's teaching is the test by which to judge visiting teachers. Those who 'go beyond' it cannot be from God. John is combating the same sort of trouble here as in his first letter. From the start of the Christian mission there had been travelling evangelists and teachers, usually responsible to one of the apostles, who were given hospitality by the local churches. The time has come to tighten up. Those whose teaching contradicts the fundamental truth about Jesus Christ should not be made welcome.
John looks forward to a visit. There is so much more to be said than he can put in writing. The 'Children of your dear sisiter' are presumably members of John's own church.
Those who do not bring both the Father and the Son, do not welcome him and do not enter their church.
How?
May the truth and love be with me, walk in love and trust in both the Father and the Son.