We’ve been working our way through Article 29 of the Belgic Confession which gives much encouragement about local churches and our membership in them. Article 29 gives the three marks of the true church—the pure preaching of the gospel, the pure administration of the sacraments, and church discipline—and the says:
In short, it governs itself according to the pure Word of God, rejecting all things contrary to it and holding Jesus Christ as the only Head. By these marks one can be assured of recognizing the true church—and no one ought to be separated from it. 
Two things about that. One, the true church holds Jesus Christ as its only Head. Therefore, it submits to Christ’s Word in everything. It welcomes Christ’s governance over it. When it comes to all things church life, the true church turns to Christ and not societal or consumer trends. Two, no one ought to separate from the true church. Everyone must belong to a local church that practices the three marks of a true church. To be outside of the membership of a faithful local church is to be outside of the true church of Christ because the true church of Christ is expressed, seen, and experienced in local churches across the world.
Article 29 also describes the false church. This is the so-called “church” that you want to avoid. Don’t belong to a local church if it’s like this. The Belgic Confession says:
As for the false church, it assigns more authority to itself and its ordinances than to the Word of God; it does not want to subject itself to the yoke of Christ; it does not administer the sacraments as Christ commanded in his Word; it rather adds to them or subtracts from them as it pleases; it bases itself on men, more than on Jesus Christ; it persecutes those who live holy lives according to the Word of God and who rebuke it for its faults, greed, and idolatry. These two churches are easy to recognize and thus to distinguish from each other. 
As we close out our series on the marks of a true church and church membership, I want to end by directing you to one more portion of Article 29. This portion addresses those who are of the true church and gives the distinguishing marks of true Christians. This is about you and me as individuals who belong to a covenant community. The Belgic Confession says this, and please take this to heart, because it will encourage you to faithfulness:
As for those who are of the church, we can recognize them by the distinguishing marks of Christians: namely by faith, and by their fleeing from sin and pursuing righteousness, once they have received the one and only Savior, Jesus Christ. They love the true God and their neighbors, without turning to the right or left, and they crucify the flesh and its works. Though great weakness remains in them, they fight against it by the Spirit all the days of their lives, appealing constantly to the blood, suffering, death, and obedience of the Lord Jesus, in whom they have forgiveness of their sins, through faith in him. 
Who is truly united to Christ? Whose faith is sincere? Well, we can’t really see that. However, we can see fruit. How do you know how to recognize other true Christians? What do you look for? What should you see in them and experience from them?
- FAITH. True Christians receive the one and only Savior, Jesus Christ. They confess the gospel and trust in Christ for the forgiveness of their sins and for the motivation and power to obey God.
- REPENTANCE. True Christians hate their sin enough to flee from it.
- RIGHTEOUSNESS. True Christians pursue righteousness. By God’s grace and Spirit, by faith in and union with Christ, and because they belong to Christ, true Christians strive to obey God’s law with thankfulness and joy.
- LOVE. True Christians love God and those around them. Jesus told his disciples in John 13:35, “By this all people will know that you are my disciples, if you have love for one another.” Love for Christ’s church is how people can tell you belong to Christ. 1 John 3:14 adds, “We know that we have passed out of death into life, because we love the brothers.” Love is the evidence of regeneration.
- MORTIFICATION. True Christians crucify the flesh and its works by the leading and power of the Holy Spirit within them. They do this every day. Every day is a fight against the sinful flesh. Yes, they are weak. Yes, they are still sinful. But every day the true Christian strives to put to death what is earthly in them, things like “sexual immorality, impurity, passion, evil desire, and covetousness” (Col. 3:5). By the Spirit, they fight and fight and fight against the remaining weakness and sin in them. They fight and fail, only to rise again to fight again. They do this in vital union with Christ, and they do this by faith through which they receive abundant grace. You can tell a Christian by their Spirit-wrought fight against sin.
- APPEAL. True Christians constantly appeal to the blood, suffering, death, and obedience of the Lord Jesus. They draw comfort from the gospel, that Christ shed his blood for them, suffered for them, died for them, in fact, lived for them in perfect obedience to God. They find comfort and assurance in knowing that they have the forgiveness of sins in Christ.
My father has a very fruitful peach tree in his backyard. It yields peaches the size of basketballs. That’s hyperbole, but they are huge. He really takes care of his peach tree, and because it’s a good tree, it bears much good fruit (Jn. 15:5, 8). The gospel is the power of God for salvation to everyone who believes, and the gospel produces fruit in and through those who truly believe (Rom. 1:16).
I think a significant piece of fruit that the Spirit grows in believers is a love for the church, a love for their brothers and sisters in Christ. Someone cannot truly love Christ without loving the body of Christ. And this love for the body of Christ is not simply fuzzy feelings or cordiality, it is self-sacrifice for the body of Christ. John explained that if someone confesses to loving God, but they don’t actively act for the well-being of the church, his confession is a lie, and he is a liar (1 Jn. 4:20). If he doesn’t love the church, he doesn’t truly love Christ, even though he says he does.
We know that Jesus Christ truly loves God because we see His selfless sacrifice and love for God’s people in the gospel. Christ has proved that he is love. Receive the love of Christ through faith. This is the greatest motivation for faithfulness and fruitfulness, and as Christ pours his love into you, you can bear fruit for him. May the Lord richly bless you this week as you strive to love God and your neighbor.
Quotes from the Heidelberg Catechism are taken from Zacharias Ursinus & Jonathan Shirk, The Heidelberg Catechism (Manheim: Small Town Theologian, 2021).
Scripture quotations are from the ESV® Bible (The Holy Bible, English Standard Version®), copyright © 2001 by Crossway, a publishing ministry of Good News Publishers. Used by permission. All rights reserved. May not copy or download more than 500 consecutive verses of the ESV Bible or more than one half of any book of the ESV Bible.