Question: "What does the Bible say about being zealous / having zeal?"
Answer: Zeal can be defined as “focused desire, characterized by passion and commitment.” The Bible often describes God and His followers as zealous. In the Old Testament (NIV), zeal is found 16 times and zealous 6 times; in the New Testament (NIV), zeal is found 5 times and zealous 7 times (Logos Bible Word Study). Typically, the Hebrew and Greek words for “zeal” or “zealous” also carry an idea of jealousy, specifically God’s jealousy for His people and His honor (e.g., Numbers 25:11; Logos Bible Word Study).
God is described many times as having zeal. The Lord’s zeal is the cause of providing a remnant for Israel (2 Kings 19:31; Isaiah 37:32) and establishing the reign of the Messiah (Isaiah 9:7). Also, God’s fiery wrath is often tied to His zeal and directed toward the enemies of God or those who fail to listen to Him (Deuteronomy 29:29; Isaiah 26:11; 42:11; 59:17; Ezekiel 5:13; 36:5; 38:19). Jesus displayed zeal when, in His devotion to God’s glory, He overturned the moneychangers’ tables and cleansed the temple of their greed (John 2:13–17; cf. Psalm 69:9).
Followers of the Lord have also been called “zealous” in the Bible. Phineas displayed zeal for the Lord by taking action to stop a plague and judge the idolatry of Israel (Numbers 25:1–9). The Lord declared that Phineas’s zeal reflected His own zeal for His honor (verses 10–13). Elijah also demonstrated zeal for the Lord in his showdown with the priests of Baal on Mount Carmel (1 Kings 18:20–40; 19:10). The command for New Testament believers is to “never be lacking in zeal, but keep your spiritual fervor, serving the Lord” (Romans 12:11).
Zeal for the Lord is a positive attribute, but zeal can be misplaced. We can have “single-minded desire, characterized by enthusiasm and devotion” for the wrong things. Saul’s zeal was misdirected when he destroyed the Gibeonites (2 Samuel 21:2; cf. Joshua 9:15, 18–21). Paul describes the unbelieving Jews of his day as “zealous for God, but their zeal is not based on knowledge” (Romans 10:2), since, in their rejection of Christ, they “did not submit to God’s righteousness” (verse 3).
Paul himself was zealous in persecuting the church before he was saved (Philippians 3:6; Galatians 1:13–14; Acts 1:3). In his misplaced zeal, he gave approval to Stephen’s murder (Acts 8:1). After Paul was radically transformed by the gospel, his zeal was applied toward expanding the knowledge of Christ to as many people as he could (Romans 15:20). He warned the Galatians against false teachers who were zealous in trying to win the Galatians over to their teaching (Galatians 4:17).
Zeal can be good or bad, depending on its objective: “It is fine to be zealous, provided the purpose is good.” Our zeal is also to be consistent and sincere, not just to put on a show: “Be so always and not just when I am with you” (Galatians 4:18). For Christians, we should be zealous in serving Jesus and telling others of the life-saving power of the gospel (Matthew 28:18–19; Romans 3:24).