The Book of 2 John - "Searchlights from the Word" by G. Campbell Morgan.
Chapter 1
Whosoever goeth onward and abideth not in the teaching of Christ, hath not God.
2 John 9
Dr. Findlay has pointed out in his wonderful volume on the letters of John, that both the second and the third have to do with the subject of Christian hospitality. In this one, addressed to "the elect lady," perhaps a church, and perhaps a person, the persons to whom no Christian hospitality is to be extended are dealt with. These are described as "deceivers ... even they that confess not that Jesus Christ cometh in the flesh." It is with reference to such that this declaration is made. They were persons who claimed to be leaders; they were advanced thinkers, they were progressive. The Gnostic teachers of the time were claiming that while the Gospel of the historic Jesus might be all very well for unenlightened people, they had a profounder knowledge. Such were to receive no hospitality. In this warning, we find a principle of perpetual application. There is always room for advanced thinking, for progressive interpretation, for the things of Christ are as profound as God and life. We never ought to be content to tarry with the first principles of truth. We should in knowledge go on unto perfection. But there is one infallible test for such advanced thinking, for such progressive interpretation. It is that the advanced thinking do not contradict the first principles, or deny the fundamental facts of our faith - those of the historic Jesus, that of the fact that He came in the flesh. Such advanced thinking as denies these things, is not progress, but retrogression and apostasy.