RAISE YOUR HAND if you identify with this statement: “I’m better at knowing what I should do than I am at actually doing it.” Right. I didn’t see all those hands, of course, but I know they were there.

In some ways, I can be pretty disciplined. In the aftermath of the COVID-19 pandemic, for example, I found that my eating and exercise habits had slipped so badly that I had gained nearly 20 pounds, and my cholesterol and triglyceride levels had shot up alarmingly high. I decided then and there to drastically change the mindless way I had been eating. All the white flour in my diet has now been replaced with whole grains. I eat very little sugar, allowing myself only an occasional and small sweet. Most of my protein comes from lean meats, nuts, and beans. I eat lots and lots of vegetables, bought and cooked fresh. And honestly, now that this has become my lifestyle, I don’t really miss the junk. My wife says that when it comes to food habits, I’m the healthiest person she knows.

But exercise? That’s my Achilles heel. I’ve done exercise programs before, so I know what to do. Keeping it up is the problem. I’ll start a simple exercise program, be good for a few days, then stop. I’ll start again, stop again, and repeat the cycle a few times before I drop it altogether. It can be months before I muster up the motivation to start again.

I know why I should do it. It would help lower my triglycerides; there’s only so much I can do with dietary changes, and really, there’s not much more that I can change in that area. Moreover, exercises that specifically strengthen my core would help me have better posture and balance — and the older I get, the more I care about balance and stability. I have too many friends who have fallen, sometimes with disastrous consequences. Indeed, several years ago, a simple fall at home was the beginning of the end for my father.

But knowing what and why doesn’t count for much if I don’t actually do it. Nor is this only about people like myself who are aging and need more strength and stability; anyone can benefit from having a strong core.

And in a sense, so can the church. Every congregation will go through its share of challenges. How badly will they be knocked off balance? It depends on whether they’ve done the work to strengthen their core.

PREVIOUSLY, I MADE the distinction between bounded sets and centered sets as the concept applies to social groups like the church. In bounded sets, membership is determined by implicit or explicit dividing lines that determine who’s in and who’s out. In centered sets, however, the emphasis is more on the movement toward and the embodiment of a group’s core convictions. That’s not to say that there aren’t boundaries, but they can be a bit fuzzy in practice.

By using his apostolic authority to instruct other communities not to welcome the secessionists and give them a platform for their heresy, John is drawing an important boundary. But he does so in a way that also emphasizes the core.

To see this, go back and read all of 2 John — but leave out verses 4 to 6, where he stresses Jesus’ command to love one another. The letter makes perfect sense without these verses. John greets his readers in a reasonably conventional way, then warns them about those he labels as deceivers and antichrists, telling them not to welcome these false teachers into their community.

But if that was his only purpose, why speak of love? Why not just say, “Beware of the heretics coming your way — don’t let them in”? Because even if boundaries must be drawn to protect the core, it must be done in a way that embodies the core as well.

Such balance can be hard to strike. We humans are intrinsically social beings, and we easily form in-groups and out-groups, sometimes spontaneously and for the most superficial of reasons. If you don’t believe me, just take a group of strangers, randomly assign them to two different teams, and pit them against each other in a winner-takes-all competition. Then sit back and watch the fun.

And if that can happen in a game whose result has no real or lasting impact on a person’s life, what will happen when something more crucial is at stake?

We have a preexisting predilection for drawing boundaries between us and them, especially in situations of conflict. Think about the political differences that divide the church. You might be at church, chatting with someone you’ve just met. Suddenly, you realize that they’re on the opposite side of a political issue that’s important to you. Your anxiety ticks upward and so does your wariness. And the longer this goes on, the harder it is to see the other person as a fellow believer, someone dearly loved by God, and therefore worthy of your love as well.

We can get out of balance, therefore, by anxiously and sometimes unconsciously policing boundaries to keep out those who don’t think, talk, or look like us, and doing so in a way that loses sight of who we claim to be as Christians and the kind of character toward which we aspire. But the opposite kind of imbalance is to act as if loving and hospitable people should have no boundaries at all.

There’s no way to know, but I suspect that this kind of imbalance was more the situation with the community or communities John had in mind. They would have welcomed the secessionists without realizing the risk. John therefore draws a clear boundary on their behalf: Don’t let them in. But he also writes to help them strengthen their core. He strengthens their core beliefs: Jesus came in the flesh. Any teaching to the contrary is not the gospel. And he strengthens their core character: We must obey his commands, and his command is to walk in love.

In situations of conflict, our core commitments may sometimes require that we draw boundaries. But please note: just because an issue is of personal importance to us doesn’t necessarily mean that it’s therefore core to the gospel. It’s too easy to assume and proclaim that God is on our side in every debate, even as we neglect to treat one another in a godly way.

So let’s not lose our balance. We can draw boundaries when we must. But we must always be about strengthening our core: our commitment to and embodiment of the core of the gospel, the core of what we believe, and the core of who we are called to be by Jesus.