Earlier he mentions them dividing based on Christ also here
1Cr 1:12 Now this I say, that every one of you saith, I am of Paul; and I of Apollos; and I of Cephas; and I of Christ.
Examples to the flock
1Cr 11:1 Be ye followers of me, even as I also am of Christ.
Phil 3:17 Brethren, be followers together of me, and mark them which walk so as ye have us for an ensample.
In contrast to Diotrephes (loveth to be first) John says....
3John 1:11 Beloved, follow not that which is evil, but that which is good. He that doeth good is of God: but he that doeth evil hath not seen God.
Knowing a tree by its fruit, a good tree cannot bring forth evil fruit, and an evil tree cannot bring forth good fruit.
Phil 4:9 Those things, which ye have both learned, and received, and heard, and seen in me, do: and the God of peace shall be with you.
Following those same examples which are good, not those which are evil.
1John 2:29 If ye know that he is righteous, ye know that every one that doeth righteousness is born of him.
Even as he that doeth righteousness is righteous, even as he is righteous.
Just as in the same, the children of God and the children of the devil are "manifest" whosoever doeth not righteousness is not of God, neither he that loveth not his brother.
God richly bless you!