Here’s Martin Luther on how a clear grasp of the heart of the gospel brings great stability in the midst of diverse teaching.
The principal topic and sum of the Christian doctrine is this, that God has sent and given his Son, Christ, and alone through him forgives us all our sins, justifies and saves us. That you are to cling to, and nothing else.
[If we settle this, we will be] with such an understanding safe against all external masks… [but] he who does not hold this main truth, or know how to regulate everything by it, cannot avoid being deceived.
(Martin Luther, Commentary on the Sermon on the Mount, 260).
Jesus said false teachers wouldn’t just be ‘out there’ in the world, but part of the mix ‘in here’ with the church. They would be wolves in sheep’s clothing (Matthew 7:15). We won’t find them in a dim-lit, cobweb-covered ‘heretics’ section at Barnes and Noble. They’ll be next to the Bibles.
The best way to recognize and not be led astray by a wolf is to get one thing straight: to be sure of the central doctrine of the gospel. If we cling to the central truth of the gospel and “know how to regulate everything by it,” we will be able to see through a thousand lies. They may have cool video shorts. They may write bestsellers. They can say they’ve been to heaven or hell and back. They may tell hundreds of stories about prosperity for those who donate. They may call themselves Christians. But if they have abandoned “the principle topic and sum of the Christian doctrine,” it’s not an emerging Christian group or a different denomination they represent; it’s a different religion.
Those who spot counterfeit money fastest and best are those who know the real thing intimately.