How Do You Do Apologetics Across Denominational Lines

Christians disagree about baptism, the Lord’s Supper and how a church should be run, and a skeptic can fairly ask why anyone should trust a faith whose followers cannot agree. The answer is that Christians share a center. Jesus is fully God and fully man, he died for our sins and rose bodily from the dead, and salvation comes by grace through faith in him. Sprinkling or immersion, what happens at the Lord’s Supper, church government and worship style are real differences that matter deeply. They are not what makes someone a Christian, though exactly where the line falls is itself something Christians debate.

This guide builds a working map a group can use to tell what must be defended together from what can be debated charitably. You can work through it alone in about an hour, or with a group over one or two meetings. It moves in order: two distinctions, a close reading of Scripture, a test and its limits, and a practice that ends with a map your group has built. The main voice is Rev. Brandon Harris, a Protestant chaplain at Georgetown University who leads worship each week with students and ministers from several traditions, in conversation with Lisa Fields on the Jude 3 Project podcast.

First distinction: important is not the same as essential

Most arguments across church lines go wrong at this first step. People hear “secondary” and think “doesn’t matter.” So a Baptist who is told that immersion is secondary hears, your conviction is trivial, and pushes back. The pushback is fair, because the claim was badly made.

Harris avoids this mistake. Describing the temptation to get stuck on the fact that “you sprinkle and I dunk,” he calls these practices “essential to the faith, and essential to what we believe.” He does not ask anyone to stop caring about baptism. He asks a different question underneath the dispute: “what’s the core narrative about baptism and what does that mean?”

That question separates two things. One is a belief’s importance: how much it shapes worship, conscience and church life. The other is its function: whether it defines the gospel itself. Baptism is very important. For many Christians, whether it is done by immersion or sprinkling, or for infants or believers, does not decide who Jesus is or how a sinner is saved. The rest of the map is built on this difference between weight and function.

Second distinction: three layers, not two

A two-box sort of “essential” and “nonessential” is too crude. It puts a lifelong conviction about the Lord’s Supper in the same box as a preference for hymns over choruses. A better map has three layers.

1. The center. Beliefs that define the Christian faith and the gospel. Jude 3 Project names these as the authority of Scripture, the deity and humanity of Jesus, the Trinity, the bodily resurrection, salvation by grace through faith, and the gospel itself.
2. Tradition convictions. Beliefs held seriously, often for good biblical reasons, that shape a church’s life and often decide which church a person joins. Mode and timing of baptism, the meaning of communion, church government and views of spiritual gifts sit here. Faithful Christians who love Scripture land in different places.
3. Preferences. Matters of style and custom: music, service length, how formal the liturgy is. These can be deeply felt and still be preferences.

Harris puts the picture in a sentence: “I often find that the heart of the gospel is not at its fringes, but at its center.” Some things carry the weight and others lean on them.

Here is where the picture breaks. Circles suggest that the farther something sits from the center, the less it matters day to day. In practice, the second layer can shape a congregation more visibly than the first. Harris serves communion every week beside a Methodist minister and a Presbyterian minister and says plainly, “our theology around the table is completely different.” That difference shows up every Sunday. Use the circles to locate a belief, not to measure how much anyone should care about it.

A belief can also sit outside the short list of essentials and still be held firmly. Jude 3 Project treats marriage and the sexual ethic as settled positions, though they are not on its list of gospel essentials. Outside the center means “not what defines the gospel,” not “no conviction allowed.”

Reading Scripture: one apostle, two postures

The New Testament shows both firmness and flexibility, often from the same writer. Read these passages slowly. In a group, assign each passage to a different person and read them aloud in order.

Start with Paul’s summary of what he passed on to the Corinthians: “For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures; And that he was buried, and that he rose again the third day according to the scriptures” (1 Corinthians 15:3-4). The KJV’s “first of all” does not mean first in time. Many other translations render it “as of first importance.” Paul is ranking. Christ’s death for sins and his resurrection sit at the top.

Next, see how Paul guards that center: “But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, let him be accursed” (Galatians 1:8). The issue in Galatia was whether Gentile believers had to take on the law to be fully accepted by God, which reached the question of how a person is made right with God. Paul gives no ground.

Then read a different posture. “Him that is weak in the faith receive ye, but not to doubtful disputations” (Romans 14:1). A few verses later: “One man esteemeth one day above another: another esteemeth every day alike. Let every man be fully persuaded in his own mind” (Romans 14:5). Believers disagree about food and holy days, and Paul tells them to welcome one another and hold their own convictions with a clear conscience.

Observation prompts:

• In Galatians, what exactly is at stake that makes Paul so severe? In Romans 14, what is not at stake?
• Romans 14 does not say convictions about days are unimportant. It says “fully persuaded.” What does that tell you about holding a second-layer belief?
• Romans 14 is about food and days, not baptism or communion. What would you need to show before applying its principle to those questions?

Paul does not hand us a list of which modern disputes belong in Romans 14. The passages give a pattern: the same apostle is unbending where the gospel itself is threatened and generous where it is not. The sorting is our job, done carefully.

Ephesians 4:4-6 adds a further observation: “There is one body, and one Spirit, even as ye are called in one hope of your calling; One Lord, one faith, one baptism, One God and Father of all, who is above all, and through all, and in you all.” Paul can speak of one baptism for the whole church. Many readers take this to mean that the shared meaning of baptism, union with the one Lord, runs deeper than later disputes about its practice. That is an interpretation, not a ruling on anyone’s tradition, but it fits Harris’s question about the core narrative.

Two predictable mistakes, and a test with limits

The first mistake is shrinking the center to avoid conflict. A group that wants peace can quietly drop whatever is hard, until “essentials” means little more than being kind. Galatians 1:8 rules this out. Harris describes the work on his campus as asking, “what’s our core, what does it mean to be a Christian?” Asked for his own answer, he speaks as a Baptist: “we’ve been saved by faith through grace in Christ.” He adds that salvation in Christ “is both personal and social,” reaching toward the redemption of society and creation. That second claim is his own pastoral argument, and Christians weigh it differently. The first is the shared center.

The second mistake is assuming everyone already agrees where the lines fall. Harris names this as the hardest part of his work: “we all have different views on what the essentials are at times.” A map does not end that disagreement. It gives you a way to talk about it honestly instead of treating every difference as either nothing or everything.

A practical test helps. Ask three questions of any disputed belief:

1. Does this difference change who Jesus is?
2. Does it change how a person is saved?
3. Have faithful Christians who hold to Scripture’s authority held different views on it across the church’s history?

A yes to either of the first two places a belief at the center. A no to both, together with a yes to the third, usually places it in the second or third layer.

The test has a real weakness. Some traditions answer yes to the second question for baptism or the Lord’s Supper, because they understand these as means by which God gives saving grace, so for them the sacraments press toward the center. When that happens in your group, do not overrule the person. Record their placement alongside yours, and talk about what both of you still confess together about Christ’s death and resurrection. That shared confession is the ground on which the remaining disagreement can be argued with energy and without breaking fellowship.

The practice: build your group’s map

This exercise takes 30 to 45 minutes. It works alone with a sheet of paper, but it is richer with people from more than one church background. Facilitators: if your group is all from one tradition, ask each person to bring the view of a Christian friend or relative from another church, described as that person would describe it.

1. Draw three circles, one inside another. Label them “center,” “tradition convictions” and “preferences.”
2. Write down eight to ten beliefs or practices on which Christians you know differ. Be specific: infant baptism, weekly communion, speaking in tongues, bishops versus congregational votes, a fixed liturgy, the timing of Christ’s return.
3. Add the center beliefs from 1 Corinthians 15:3-4 and the list above.
4. Place each item using the three test questions. Write a one-sentence reason next to each placement.
5. Circle any item where your group disagrees about placement. Do not force a vote. Have someone who places it differently explain the reason in their own words.
6. For one circled item, have a person from the other side restate that reason until the first person agrees the restatement is accurate. Only then may anyone respond.
7. Finally, pair up. One person plays a friend with no faith who says Christians cannot even agree on baptism. The other answers using the map: name where Christians differ, show that the difference sits outside the center, then state the center plainly in three or four sentences. Switch roles.

Step six is the heart of the exercise. Harris says “being bold and being humble go hand in hand,” and he describes boldness as being able to say “this is what, through my study of scripture and through church tradition and history, I’ve come to believe.” Humility, in his account, means truly listening and recognizing that other traditions have gifts to offer. He draws on the Book of Common Prayer in a student crisis without becoming Episcopalian: “yes, we draw certain lines and boundaries, but we should also allow ourselves to be permeable.” Lisa Fields makes the same point from the other direction: people in other traditions “have legitimate reasons that they believe that,” and dismissing those reasons stops the conversation.

Step seven connects the map to its purpose. Harris wants believers to be able “to present a common front of what does it mean to be a Christian,” and he says the next generation does not care what background you are from: “they just wanna know who Jesus is.” That question belongs in the center circle, and the role-play gives the group practice answering it together.

Facilitators should watch for one pattern. When a person feels a conviction is being moved outward, they may hear it as an insult. Return to the first distinction: placing a belief in the second layer says nothing about how much it matters to that person or to their church.

Discussion questions

1. Before this study, which belief did you treat as central that you now think belongs in the second layer? Or the reverse? What moved it?
2. Galatians 1:8 and Romans 14:1 come from the same apostle. In your own words, what decides which posture Paul takes?
3. Choose one second-layer conviction you hold. Can you explain the strongest reason a faithful Christian holds the opposite view, in a way they would accept?
4. Where does your church or family tend to make the center too small, and where too large?
5. Harris argues that salvation is both personal and social. Where would you place the social part of that claim on your map, and why?
6. If someone in your group places baptism or the Lord’s Supper at the center, what do you still share with them, and what would it take to defend that shared center together?

A question to carry

The next time you hear Christians argue, ask the question that matters most for any defense of the faith: is this argument about the center, or is it keeping someone from hearing the center at all? Lisa Fields offers a reason to take that question seriously. Believers from many traditions will share eternity, so “you have to learn how to interact on earth.”