As Charles Spurgeon put it, “To pursue union at the expense of truth is treason to the Lord Jesus Christ.” So we must be willing to abandon Christian unity when the truth of the gospel is at stake. But so often it is not, and it is a matter of getting along with other believers who have a different take on various theological issues, often doctrines of lesser significance.

Those who think Christians should be in full agreement on all matters of doctrine need to bear in mind that this may seem to be some sort of ideal, but it is often not the reality. And we see this when the church was still in its infancy. As I read through Acts 15 again today I was reminded of two very clear cases of division.

The bulk of the chapter deals with the Jerusalem Council. The first two verses lay out what that was all about: “But some men came down from Judea and were teaching the brothers, ‘Unless you are circumcised according to the custom of Moses, you cannot be saved.’ And after Paul and Barnabas had no small dissension and debate with them, Paul and Barnabas and some of the others were appointed to go up to Jerusalem to the apostles and the elders about this question.”

A second dispute (verses 36-41) was not theological in nature as much as a difference in missionary tactics. And it was quite a strong difference. As we read in verse 39: “And there arose a sharp disagreement, so that they separated from each other.”

I have of course often written about theological differences. One main point I keep seeking to emphasise is that on secondary doctrines there should be room to move, but on fundamental doctrines we need to hold the line. See this piece for example.

Here I want to revisit this issue as I do several things: look at two books that speak to this – an old one and a new one – and then provide a few recent examples of theological differences I was involved in. As to the books, I recently reread Mere Christianity by C. S. Lewis.

My original paperback copy of the book is nearly 50 years old now, well worn, and covered in highlighting. So I bought myself a brand-new hardback so that I might read it afresh. And one thing jumped out at me as I started to reread the classic work.

As Lewis discussed in his preface why he was promoting a “mere” Christianity that most believers would agree to, he said this: “There are questions at issue between Christians to which I do not think we have been told the answer.” That was a great relief to me.

That is because so often I toss and turn at night asking God for some real clarity on any number of biblical and theological topics. I am a teacher. I have the gift of teaching, and I have taught for nearly a half century now, whether in the classroom, or more recently on my website and on the social media.

I will be held to account for my teaching, so I want to make sure I get it right. But some issues we may not get final full disclosure on – at least in this life, and at least on some of the less vital doctrinal matters. So that one line was of real help to me. I do not necessarily have to have a full understanding of everything.

The second book I want to mention came almost 80 years after Lewis’s volume first appeared. I refer to Rhyne Putman, When Doctrine Divides (Crossway, 2020). This is a very helpful discussion of these very matters, and deserves a proper review at some point.

But for now I can mention a few things as found in its 300 pages. In his introduction he explains where he is coming from: “Unlike the spirit of theological minimalism that permeates so much of the ecumenical conversation, the discussion of doctrinal disagreement in this book celebrates both doctrine and difference… As lovers of the truth, we should not reduce our doctrinal disagreements to much ado about nothing. Healthy disagreements are an important part of sanctification and growth in grace.”

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