As we're looking to cooperate with other believers, we want to make sure we share the apostles' teaching, not destructive heresies.

There is no agreed upon list of which errors should be called heretical, and it's probably not useful to refer to all errors as "heresy." Doing so just ratchets up the emotional heat without adding light to a conversation. Not all errors are the same. In fact, it's dangerous to treat all errors as the same. A misunderstanding of church membership is less important than a misunderstanding of the person of Jesus Christ! Some errors must be corrected; others can be endured for a lifetime.

Determining which errors can be borne with and which require separation requires us to understand the significance of the doctrine in which the disagreements occur, and even of the days in which a particular doctrine is in dispute. Just like some organs are more important than others, so some doctrines are more central than others. Our understanding of Christ's work on the cross is more important than our view of the Sabbath, just like our heart is more important than our appendix. A human can survive the removal of his wisdom tooth or his appendix, but not his heart!

How To Learn

How do we learn what we must agree on? Let me suggest three ways: through the Bible, through our church, and through our conscience.

We learn the truth fundamentally, supremely, finally, and mostly through the Bible. This is God's Word written. Study your Bible. Get to know God's Word well. Always be growing in your understanding and your love for it. Read Psalm 119 in your quiet times for a month in order to meditate and grow in your appreciation for the great gift to us of God's Word.

But God does not intend us to be earthly orphans, self-taught, self-regulating, self-centered. God has called us to belong to local churches that teach the Bible accurately and that are full of people whose lives show the fruit of his Spirit. Good teaching should bear good fruit. The elders in our churches should be able to teach us God's Word, which means we should submit ourselves to them and their teaching. When teachers teach as they should, Christians together in a church will have a clear grasp on the gospel that saved them. (Paul assumes in Galatians 1:8-9 that this would be the case.) Ultimately, then, it is the duty of the local church to define what we must agree upon to be a Christian, and to be a member of that congregation.

We learn also through our consciences. Each of us has a conscience. By the Fall, the conscience was radically harmed, but this important aspect of God's moral image has not been eliminated from our character. We all have an inherent sense of right and wrong. But that sense is inherent, not inerrant. Many people today treat their internal moral sense as their own unique god within, but the conscience must be corrected, trained, and taught, and it is our duty to do that according to the Scripture.

Clarity and Agreement

How can you tell if a doctrine is important and worth seeking agreement upon? Here are several tests for answering this question:

  • How clear is the doctrine in Scripture?
  • How clear do others think it is in Scripture (especially those you respect and trust as teachers of the Word)?
  • How near is the doctrine (or its implications) to the gospel itself?
  • What would be the practical and doctrinal effects of allowing disagreement in this area?

The people of God have always recognized that both summarizing and teaching the heart of the truth is important. So God gave his people a summary of his law in the Ten Commandments (Ex. 20). Moses in Deuteronomy 6 provided another summary on how they were to teach their children. And Christians from the earliest times have used the summaries provided by catechisms to prepare individuals for baptism—which is how the Apostles' Creed was originally used. The church father Vincent of Lerins said in the fifth century that we should believe what has been believed always, everywhere, by all.