Finding Christian Unity Amidst Theological Diversity

what is a theological orthodoxy

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.

Kaeli Joyce studied classical civilizations and religious studies at Gonzaga University. She currently serves as a student mentor for Youth With A Mission’s online School of Biblical Studies.


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  1. Harry Court says

    Great article. I would humbly suggest another central criteria – is the “gospel” preached? In fact do people know what the gospel is?

  2. No one rejected the deity of Jesus or the Godhead in Corinth and yet Paul condemned them for their division in 1 Corinthians 1. How does that harmonize with the view presented in this article?

  3. Friedrich says

    Perhaps some are not completely orthodox in their beliefs, but they are still in unity because they have believed upon the One who was sent for them. Perhaps our unity is about what He has done for us, and then as much about how we live out that love and walk in that light and bear one another’s burdens in humility, grace, truth, and love.

  4. Hi Kaeli,

    Very nicely done article. Some comments I have would be, respectfully, I do not see the body of Christ (the church) broken, no, not in any way, shape or form.

    Jesus’ prayer you cited in John was answered and IMHO, one needs to go back much earlier in church history to realize this, but the fact is the Church has never been broken, even during the dark ages there was always (call it a remnant) of the original faith, or “The Way.” Logos had some excellent resources on this, if you do a search using by the word “Waldesians” (my spelling could be a bit off on that) you will find a number of resources, but even early church history up to the 3rd Century also catalogs the beliefs of the wary church with the main source being scripture.

    I am also a bit puzzled why you cite an author who claims what are the only two doctrines essential to Christian unity, began with he Chalcedon Creed. Is there a particular reason for this?

    I ask, since I could just as easily claim the ὁμοούσιος (omoousios) the relationship of each person in the Godhead to each other being of “one substance” and Triune. Or, the ὑπόστασις (hypostasis) the fully divine and fully human nature of Christ. Both are clearly (authorship controversies aside) affirmed in the Athanasian Creed as one example as are both clearly illustrated throughout the New Testamwnt as well as the OT, in both [Types] and scripture.

    That aside, if we make a claim all Christian denominations who accepts these beliefs are part of the body of Christ (the church) well, without calling attention to specific denominations, ALL except those who adhere to a very specific theology, a simple search conducted will show as one example many Protestant denominations, now, not only marry but ordain gay ministers.

    In fact it’s now hit a majority. While there are parts of many Protestant denominations that still cling to what can be called the traditional or conservative faith, the majority are in apostasy.

    I do not see this to mean the true church (the body of Christ) is fractured. I would say His true church based on biblical doctrine and NOT tradition and certainly not changing to accommodate the times, is thriving, however small in number it may be.

    Jesus said there will be very few that enter the narrow gate.

    On the other end of the spectrum we have the Roman Catholic Church who certainly believe in the Trinity and the Hypostatic Union, however, how does this in any way excuse one of its many false doctrines, topped of by the claim of which an infallible human pope who is the head of their church? Christ is the only head of the church. This does not mean some who attend a Roman Catholic Church are not one of God’s elect who will be led to the truth.

    Lastly, I have brothers and sisters in Christ who do not share my specific beliefs which happen to be that of a Premillennial Reformed Baptist. This does not mean because someone is reformed and believes in a Covenant Theology, or perhaps does not share all 5 points of my reformed belief, does not make them not part of the church.

    However, if a denomination claims, for example, that salvation is not through faith alone and one must “do something of merit” to earn salvation or worse, that it can be lost, I cannot reconcile such heresy which is so plainly clear in the Word of God.

    I suppose a summary of my beliefs would be to say, that to support an ecumenical mindset believing this will result in unity (based only upon two of most obvious scriptural truths which are crystal clear and have no need of being formalized in a creed, (namely the Trinity and the Hypostatic Union) are simply not enough.

    Galatians and much more in scripture makes this crystal clear. Apologies if I read your article wrong.

  5. This is a great post, and such a critical issue today. I loved what you said in the beginning about the implications of getting this wrong being pretty significant. I think that the mindframe of believers in today’s world needs to shift from ‘what keeps us apart’ to, ‘Let’s agree on what we can agree on so that we can show a unified face to the lost and dying world around us’. When brothers (and sisters) dwell together in unity (Ps 133) it is amazing what can be accomplished!

  6. Christ is looking for a “Pure” church, one that is not a compromising church. Jesus told us what He considers unity to be in John 17:17-21 “Truth”. We are made Holy and Pure by the truth, and we are to be unified by the truth not by compromise. Christ is looking for unity, but not for “unity’s” sake but for the sake of the truth. All those that have the Truth of Christ will unify together because of the truth.

    Truth is more important than unity. Matthew 10:34 says “I came not to send peace on earth: I came not to send peace, but a sword”. What sets us at variance with each other is compromise of Christ’s truth.

    The reason that there are so many different denominations is because of compromise of the Truth. If the word of God is our guide then we should all be unified on what that Word actually says.

  7. The article is called “Finding Christian Unity Amidst Theological Diversity” but in the URL it looks like it was originally called “What beliefs are essential to theological orthodoxy.”

    Pardon my heresy here (wink), but knowing the present and previous article titles highlight, for me, what is necessary for unity. It is to be inclusive of other ideas and beliefs rather than exclusive. Drawing boundaries about essential beliefs and orthodoxy is a good thing to do, unless it is being done to keep some people in and some people out. Similarly, guarding against heresy is good, unless it is being done in a way that condemns and makes outcasts.

    If we want unity – and I hope we do – we will need to start by recognizing the things that unify us with whoever we are with. It might not be anything more than the name “Jesus” – a name, for example, that Christians and Muslims share. Will we ever unify our beliefs? No, not unless one of us changes religions. But the name “Jesus” is something we have in common. He’s someone we can discuss, about whom we can (charitably) disagree, and who, perhaps in the end, we can recognize as being someone whose importance we both recognize and confess. If we are capable of that kind of conversation, we can perhaps make inroads to deeper relationship and trust.

    Your atheist friend may share the name “Jesus” too – seeing him as an important teacher, or even if they’re one who denies a historical Jesus, perhaps acknowledging that the way he taught us to live is something beautiful to which we can aspire. Perhaps they don’t see that either, but agree that there is a central force guiding the world. Hey! We believe that, too. As we discuss this mysterious guiding force, with neither of our beliefs hidden, perhaps we will share one another’s insight and perspective, even if we ultimately disagree with one another’s conclusions. And we can have unity.

    Unity is a decision we make, and it is made possible by an approach we choose to take to others. Unity does not mean “theological agreement” or even “agreement on the essentials.” It means that we choose to be and work to be unified – even when we disagree on the essentials.