1. II. Light and Darkness (1:5-2:24)
    1. D. Test of Truth (2:18-2:24)
      1. i. Danger of false teachers and Antichrist (2:18-2:19)
Thematic Relation: Many are teaching false ways. These are against God and Christ.

Some Key Words

Antichrist (antichristos[500]):
against Christ; an opponent of Messiah;
Of (ex[1537]):
the point whence action of motion proceeds, from; out of, away from.
 

Paraphrase

18 We can tell it is the last hour, because there are many false teachers about, 19 who come out of the true church, but are not truly of the true church.

Key Verse

2:19 - the falsehood begins within the true church, but cannot stay there. So, it goes forth, and can be recognized for what it is; but by then the damage is largely done.

Thematic Relevance:

 We must be prepared to tell apart the true and the false. That is in part why so many tests are given in this book.

Doctrinal Relevance:

 The endtimes come (and have been coming for centuries, now).

Moral Relevance:

 If we can't recognize the true follower, and the true teacher, we will be led astray. It is imperative that we know God's Word and will intimately, that we may not be fooled.

Some Parallel Verses

2:18
Ro 13:11 - the time grows short. 1Ti 4:1 - and the spirit clearly speaks of people falling away to false doctrines. 1Pe 4:7 - as the end is near, we ought to be firmly set in prayer. Mt 24:5 - Christ warns of antichrists coming in His name. Mt 24:24 - misleading even the elect, if possible. 2Jn 7 - one sign of antichrist is the denial of Jesus' being both God and man. Mk 13:22 - parallels Mt 24:24.
2:19
Ac 20:30 - Paul warns that false teachers will arise amid the church. 1Co 11:19 - While this speaks of becoming evident, it's not in the same sense. In this case, it's a matter of personality conflict, not an issue of falsehood.

New Thoughts

It occurs to me that this is a bit of scripture that can be (and doubtless has been) used against any number of 'younger' denominations. I can see the RC using this to explain the Protestants, and the Protestants in turn using it to explain the Pentecostals, and so on. What a mess. On the other hand, the warnings are clear, and hardly limited to the few scriptures noted here. We must recognize the dangers of the times, must be clear enough on sound teaching and doctrine to recognize the falsehood immediately. God's word is pretty clear that it will be exposed eventually, but not before some damage has occurred. Can it impact the elect? I don't believe so, for their election is sure. Yet that clearly remains a target for the enemy, who would like people to believe that he has managed such a thing. Stand firm, and remain in the word!