The term ψευδάδελφος designates an individual who claims to be a fellow believer while actually standing in opposition to the gospel. A “false brother” is not merely immature or erring, but consciously or stubbornly misaligned with the saving truth of Jesus Christ while presenting himself as part of the Christian family. Scripture treats such a person as a covert threat to the purity, unity, and liberty of the church.

Occurrences in the New Testament

• 2 Corinthians 11:26 – “I have been in frequent journeys, in dangers from rivers, in dangers from robbers, in dangers from my countrymen, in dangers from Gentiles, in dangers in the city, in dangers in the wilderness, in dangers at sea, and in dangers from false brothers.”
• Galatians 2:4 – “This issue arose because some false brothers had infiltrated our ranks to spy on the freedom we have in Christ Jesus in order to enslave us.”

Historical Setting in the Pauline Epistles

Paul repeatedly faced adversaries masquerading as believers. In Galatia they pressed circumcision and Mosaic obligations upon Gentile converts, undermining justification by faith. At Corinth their presence compounded the apostle’s hardships, ranking alongside perils such as robbers and raging rivers. These pretenders disrupted fellowship, cast doubt on Paul’s apostolic authority, and sowed legalism or moral laxity depending on context.

False Brothers and the Gospel of Grace

Galatians 2 underscores how “false brothers” target Christian liberty. By insisting on works of the Law, they threatened to “enslave” the church—contradicting the finished work of Christ. The challenge forced Paul to defend the gospel publicly, demonstrating that tolerance of counterfeit brethren where the gospel itself is at stake is no virtue. Authentic unity can never be achieved at the expense of doctrinal truth.

Marks of False Brothers

1. Infiltration rather than open opposition (Galatians 2:4; Jude 4).
2. A message that adds to or subtracts from the sufficiency of Christ (Acts 15:1,5).
3. Desire to control or exploit, whether through legalism (Galatians 4:17) or licentiousness (2 Peter 2:1–3).
4. Hypocrisy—outward piety masking unbelief (Matthew 7:21–23; 2 Timothy 3:5).
5. Resistance to apostolic authority and Scriptural correction (3 John 9–10).

Pastoral Response

Paul’s pattern offers a threefold approach:
• Discern – test every spirit and teaching against the apostolic gospel (1 John 4:1).
• Confront – oppose publicly when core truth is endangered, as he did “to their faces” in Jerusalem (Galatians 2:5).
• Protect – refuse to yield “even for a moment” so that “the truth of the gospel would remain” (Galatians 2:5).

Implications for Church Discipline and Fellowship

Church leaders must maintain doctrinal gates, not from a spirit of suspicion but of stewardship (Titus 1:9–11). Fellowship is grounded in shared faith in Christ’s atonement, not in mere verbal profession or cultural commonality. When a professing believer persistently propagates error or division, Matthew 18:15–17 and Titus 3:10–11 prescribe measured, loving discipline for the sake of restoration and the congregation’s welfare.

Relationship to Other Biblical Warnings

The reality of false brothers stands alongside wider warnings against false prophets (Matthew 7:15), false teachers (2 Peter 2:1), and antichrists (1 John 2:18). Together they testify to the ongoing spiritual conflict in which Satan masquerades as “an angel of light” and his servants as “servants of righteousness” (2 Corinthians 11:13–15). The church is therefore called to persistent vigilance and dependence on the Spirit and the Word.

Encouragement for Discernment and Assurance

While Scripture soberly alerts believers to impostors, it also offers assurance: “The Lord knows those who are His” (2 Timothy 2:19). Believers who walk in the light, love the brethren, and hold fast to apostolic teaching need not live in fear. Rather, they are exhorted to grow in knowledge (Philippians 1:9–10) and to build one another up in the faith once for all delivered to the saints (Jude 20). Genuine brotherhood, founded on the gospel, is marked by truth, love, and mutual submission to Christ.

Conclusion

The term ψευδάδελφος reminds the church in every generation that not all who claim Christian identity truly share saving faith. Its two New Testament occurrences portray the subtlety of the threat and the necessity of resolute, gospel-centered response. By clinging to Scripture, exalting Christ alone, and exercising wise oversight, the church may guard its liberty and display the authenticity of the family of God.