Peter's warnings in the second chapter of 2 Peter are a potent reminder that false teachers will come from within the Church and turn many away from holy living and pure doctrine. While the warnings are not particularly enjoyable to read, they do serve as necessary warnings against what has happened in the past and will happen in the future. The Old Testament believers and the early Church faced false teachers. Our current generation is also being influenced by false teachers. Because of this, we do well to heed Peter's warnings and to speak out against false doctrine and those who propagate it.
But false prophets also arose among the people, just as there will also be false teachers among you, who will secretly introduce destructive heresies, even denying the Master who bought them, bringing swift destruction upon themselves. Many will follow their sensuality, and because of them the way of the truth will be maligned; and in their greed they will exploit you with false words; their judgment from long ago is not idle, and their destruction is not asleep.1
This morning, I came across this commentary on 2 Peter 2:1-3 by D. Martin Lloyd-Jones which was originally published between 1948 and 1950. He was a Welsh pastor known for his understanding of the Scriptures and his opposition to liberal Christianity. When Lloyd-Jones wrote his commentary on 2 Peter, some were calling for unity without purity of doctrine. With the warnings of 2 Peter 2 in mind, he wrote these warnings about ecumenism.
The whole emphasis at the moment is that we should all be getting together and forming great organizations. The concern is not so much as to the truth of the message, but to gather ourselves together into one great community. The tendency today is to minimize truth in favor of organization, and men are telling us with unwearied reiteration that the greatest tragedy of the world is the disunited church. But the tragedy, the greatest tragedy, as I understand the New Testament, is not the disunity of the church, is not the fact that the church is divided into groups and denominations, is not that we are not all in one organization, but that all the sections are preaching a false message and there has been a departure from the truth of God as it is in Christ Jesus. If we were all brought together and formed into one organization, that is no guarantee that the message preached would be true. There are false teachers; there were in the Old Testament and there are and always have been in the church.2
The modern ecumenical movement leads to a minimizing of doctrinal differences for the alleged greater good of the Church. Sadly, this idea leads instead to a steady decline of doctrinal purity. While we should seek unity amongst our Christian brothers when possible, unity must always proceed from pure doctrine and practice. As Peter points out in his second epistle, there is too much at stake. So, take heed to his warning and guard yourself against the false teaching that has pulled so many people down. Remember what God has done for you (2 Pet. 1:1-4), diligently add godly character to your faith (2 Pet. 1:5-11), and follow the divinely inspired Scriptures (2 Pet. 1:12-21) as you seek to guard yourself from anything that would pull you away from the Lord.
2D. Martin Lloyd-Jones, 2 Peter, (Carlisle: The Banner of Truth Trust, 1983), 128-29.