Finding Christian Unity Amid Theological Diversity

It’s common today to hear of the fractured church, the shattered church, the hopelessly broken church. Estimates of the number of denominations can be disheartening, ranging from several hundred to tens of thousands, depending on how you define “denomination.” These statistics are disconcerting to some in light of Christ’s prayer in John 17:21, which sets the stakes for unity pretty high: Jesus asked God the Father “that they may all be one, just as you, Father, are in me, and I in you, that they also may be in us, so that the world may believe that you have sent me.” The oneness of the church is a sign and witness to the world that Jesus was who he said he was. The implications of getting this wrong are significant. However, by determining what beliefs are essential to orthodoxy and what are not, we can confidently serve alongside Christians with whom we disagree on the nonessentials—thus living out to a greater extent the unity Jesus prayed for.

It seems crazy to me now, but when I was growing up in the church I never considered the differences between my own faith and those of other Christians. I was contentedly blind to any disunity. The way I saw it, I was a Christian, and there were other people who weren’t Christians. As Christians, we believed all of the things Christians believe, and everyone else had a wide variety of non-Christian beliefs. Somehow it just made sense to me that if the faith of all Christians was centered on the same God, was being informed by the same Scriptures, and had grown out of a shared history, then we probably would have developed a fairly uniform set of doctrines and practices in the last 2,000 years.

The kind of unity I had in mind does, in some sense, exist, and although I didn’t know it then, it has a name: orthodoxy. Despite our major cultural and theological differences, there already is a significant degree of unity in the church, in that there are certain things all churches necessarily affirm in order to be recognized, historically speaking, as Christian. There is a oneness in the church that rests upon the core and essential doctrines of Christianity found in the Scriptures and conveniently distilled in the Apostles’ and Nicene creeds. Many evangelical churches don’t recite these creeds, but I would contend that they all adhere to the doctrines set forth in the them, even if not consciously.

As we build unity in the church, we must recognize which doctrines are non-negotiables. These are the “roots” of our faith—those fundamental doctrines that tether all of us to this thing we call Christianity.

What is Christian orthodoxy?

In his Mobile Ed courses on historical theology, Dr. Roger Olson, a professor of theology and ethics at George W. Truett Theological Seminary, identifies the two most fundamental and universal doctrines of the church: “From Chalcedon in 451 on, even up until and through the Protestant Reformation, these two great doctrines, or dogmas, of the Trinity and the hypostatic union, really define Christian orthodoxy. They are necessary for defining Christianity, if not sufficient. Some churches will add other doctrines as important and necessary, but throughout the world . . . these two doctrines—the deity and humanity of Jesus Christ and the Trinity—really summarize the essence of Christian orthodoxy.”

If the doctrines of the hypostatic union and the Trinity are the most condensed summaries of Christian doctrine, we can observe the Apostles’ Creed for a little more definition. This statement declares that God the Father is the creator of everything. It recognizes Jesus as the Son of God and as our Lord, and it affirms the central story of the gospel: Jesus’ incarnation, death, resurrection, ascension, and future return as judge of the world. This creed affirms belief in the Holy Spirit, and it speaks to the character of the church and relationship among the “saints.” It affirms the reality of the forgiveness of sins, resurrection of our bodies, and eternal life. Historically speaking, any Christian who holds to these doctrines passes the test of theological orthodoxy.

While we might wish that we could look into people’s hearts to know if they are a true brother or sister in Christ, there is no way to do that. Nevertheless, at the very least, anyone who adheres to these doctrines—which have been used as a measuring rod over the ages—is considered by Christians to be theologically orthodox.

What about the rest of my beliefs?

One way I’ve seen Christian beliefs conceptualized is by picturing three concentric circles. In the innermost circle you find the things that make you a theologically orthodox Christian—for instance, a belief in the divinity of Christ. Things in this circle are actually appropriate to divide over, because the sum of them equals Christian orthodoxy.

In the next ring you have things that define you as a Presbyterian or a Methodist or an Anglican, and they are not matters of Christian orthodoxy. These beliefs are often expressed by official church documents, such as the Lutheran Catechism, the Westminster Confession of Faith, or even the by-laws or charter of a particular denomination. Those foundational documents lay out the theological positions of a particular subset of believers. An example of something in this category would be the acceptability of the ordination of women. While these issues should not divide believers, they do, practically speaking, segment the church.

In the outermost circle are the things that are nonessential and up for debate. These should not be defining or divisive. The fact that these beliefs and practices are nonessential does not meant that they don’t matter, only that they are not clear or crucial enough to develop doctrines on. An example of something that falls in this group would be a conviction about the identity of the Nephilim in Genesis.

Is orthodoxy enough?

The point of grouping our beliefs into these categories is not to say that nothing outside of the innermost circle matters. Certainly all of our beliefs, regardless of which circle they fit into, are meaningful, as they will determine our priorities and influence the way we live. We are each responsible before God to seek the truth and live in light of it. The point of categorizing our beliefs is rather to help us see where we can more readily join together in the work of God.

While church A and church B might have vastly different views of the role that baptism plays in the life of a believer, and church B and church C might have opposing understandings of eschatology, and church A and church C might have completely different standards for worship music, the fact is, since they all believe that Jesus is the way to salvation, they can mutually encourage each other in the work of evangelism. Since they all believe that God is the creator of everything, they are free to collaborate on projects that protect what he has made. Since they all believe in the Lordship of Christ, they can gather and pray together in Jesus’ name.

There will of course be limitations because of our differences, but these limitations should not keep us from stretching ourselves to work together for the kingdom in whatever ways are currently possible. While Christian orthodoxy is not the full definition of church unity, it should go a long way toward preventing us from alienating other believers and toward accomplishing shared goals. Christ’s body is not broken beyond repair; there is hope for the fragments to come together. And as we grow in unity, we present an image of Jesus to the watching world.

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Continue exploring the historical development of doctrine—and its implications for the church today—with Roger Olson’s Introducing Historical Theology Mobile Ed bundle.