The last verse of the book of 1 John has always puzzled me. "Little children, keep yourselves from idols." That seems strange to me. Normally a letter ends with a final greeting and a grace wish of some sort.
Three observations, if you will.
1. First, notice that the command is in the plural. It's not directed to individuals within the church as much as it is directed to the congregation as a whole.
2. Secondly, observe that the command is in a tense that implies urgency. It's as though the author is saying, "Do this, and do it NOW. It's urgent."
3. Finally, what danger was John warning against? In light of the theme of the letter, it seems that he had in mind any untrue mental image of God that had been fashioned by the false teachers. God's Word reads, "Keep yourselves from false gods." In short, John seems to be warning the church against any form of error or heresy that replaces God's authority with human authority. This warning is very relevant today!
When I lived in Europe, I thought to myself that there were some countries that gave me great hope about the future of Christianity within their borders. But there were other countries where I thought, "I'm not sure genuine Christianity will exist here in the near future." What's happening today in Germany is perhaps a good example. A good number of state church bishops have clearly violated the biblical teaching on marriage. Both Protestants and Catholics are between a rock and a hard place. To avoid supporting the faithless bishops one has to formally "leave" the church and is thus denied the sacraments. Many leaders simply do not believe in the word of God and seem to care only for their job security, which is provided by the state. Under the guise of "We want to bring people back to the church," the church is dying in the name of compromise.
Let's not forget that John's purpose in writing the book of 1 John was polemical, at least partly. It was called forth by an urgent situation in the church of his day, namely the insidious propaganda of certain false teachers who are "trying to lead you astray" (2:26). He insists that they are deceivers and antichrists because the substance of their teaching is to deny basic apostolic doctrine.
Against this background, 1 John sets forth three tests of faith based on belief, holiness, and love. These tests will enable believers to "know that we know God and are in him" (2:3-4). It seems to me that these tests are as sorely needed as they are sadly missing in the church today, and not only in Europe.