Heartfelt Love: Serving the Lord with Diligence and Zeal

The Christian life is one of love: active, holy, and self-sacrificing. In Romans 12, the Paul provides a portrait of sincere, non-hypocritical love in every area of life: personal devotion, community life, daily interactions, and even conflict. We have already considered that this love is holy and humble. In v. 11, Paul turns our focus to what it means to love through service. He shows that the love God requires of his people is diligent, fervent, and directed towards the Lord.

Christian love is not passive; it is zealous and heartfelt. Paul exhorts believers, “Do not be slothful in zeal, be fervent in spirit, serve the Lord” (v. 11). This verse challenges us in three vital ways: to pursue diligence, cultivate inner fervency, and dedicate our service to the Lord himself.

The phrase “not slothful in zeal” calls Christians to earnest, energetic love. “Slothful” suggests a sense of hesitancy or lagging. Paul urges believers not to be slow or indifferent in matters of Christian duty. Our faith must be alive and active, not marked by spiritual lethargy. As the CSB translates it, “Do not lack diligence in zeal.”

Dwight L. Moody once advised new believers to find a church and “get to work,” understanding that serving Christ through the church is vital. Love that merely talks but fails to act is not biblical love. As John exhorts, “Little children, let us not love in word or talk but in deed and in truth” (1 John 3:18). We cannot love Christ without loving his body—the church—and we cannot love the church if we are unwilling to actively serve it.

This calls us to examine our attitudes toward ministry. Do we merely fill a role or seek to go the extra mile? Do we give our best to God, or just our leftovers? Do we serve with our might (Ecclesiastes 9:10) or simply offer the bare minimum out of a sense of rote duty? Diligent love means serving the needs of the saints even when no one is watching.

The second exhortation—“be fervent in spirit”—calls for a vibrant, glowing inner life. I say “glowing” because the Greek word translated “fervent” means to boil or glow with heat. It stands in stark contrast to the lukewarmness condemned in Revelation 3:16. This kind of fervency cannot be manufactured; it comes from within, driven by a Spirit-empowered heart.

It is possible that Paul is talking of the Holy Spirit here (see the CSB, which translates “be fervent in the Spirit”) but the context seems to better favour fervency in our spirits. Christian fervency is not emotionalism but a steady and passionate commitment fuelled by the Holy Spirit’s presence in our hearts (Ephesians 5:18).

How do we cultivate fervency? It begins with a robust devotional life. Psalm 1 teaches us that the one who delights in God’s word and meditates on it “day and night … is like a tree planted by streams of water” (Psalm 1:2–3). Such a person will not wither but bear fruit in season.

We also rekindle fervency by reflecting on our salvation. Romans 7:6 tells us that we are delivered from the law “so that we serve in the new way of the Spirit and not in the old way of the written code.” The more we understand God’s grace in saving us, the more our hearts will overflow with zeal.

Rest also plays a vital role in developing and maintaining fervency. Without a regular rhythm of sabbath, we risk burnout. Rest renews strength and preserves fervency.

Lastly, we benefit greatly from surrounding ourselves with zealous believers. Proverbs 27:17 says, “Iron sharpens iron, and one man sharpens another.” Spending time with those who are passionate for the Lord helps stoke our own spiritual fires.

Paul completes the verse with the exhortation to “serve the Lord.” We must remember that, even as we love people by serving them, ultimately we are serving the Lord. This elevates even the most mundane task to the level of worship. Whether it’s teaching children, stacking chairs, or giving generously, all should be done “as to the Lord and not to man” (Colossians 3:23).

“Serve” is a strong word that implies bondservice. It speaks of complete ownership and surrender. We are not our own—we were “bought with a price” (1 Corinthians 6:20). Therefore, our service is not optional; it is the natural response of redeemed hearts.

Good doctrine helps to deepen our devotion. Specifically, we must develop a health theology (doctrine of God), soteriology (doctrine of salvation), and, to a degree, eschatology (doctrine of the last things). As we grow in our knowledge of God’s majesty and holiness (theology), we will desire to serve him more. As we develop a deeper recognition of our sin and the greatness of saving grace (soteriology), it will fill us with joyful gratitude, which will fuel eager service. As we remind ourselves that Jesus is returning as the Judge of all humanity (eschatology), it will motivate us to serve him with urgency and faithfulness (see 2 Corinthians 5:10-11).

The practical application of this verse is far-reaching. It applies to husbands and wives (see Ephesians 5:22, 25), parents and children (Ephesians 6:1), employees and employers (Colossians 3:23), and, of course, as the immediate context suggests, church members. No task is too small when done for Christ. Tertullian once declared, “Eighty and five years the Lord has not failed me; how can I do otherwise?” That spirit of devotion must mark every Christian.

Romans 12:11 calls believers to embody heartfelt love through diligence, spiritual fervency, and focused devotion. We must serve the Lord—not out of obligation, but from a heart that knows his grace and yearns to reflect his glory.

“Do not be slothful in zeal, be fervent in spirit, serve the Lord.” May this command shape our lives, stir our hearts, and deepen our love for the one who gave all for us.