What does Philippians 3:2 mean?

This verse is summarized by the words "look out." Paul is giving specific warnings about certain groups, who seem to have been troubling the Philippian Christians. Paul might have heard of these struggles from Epaphroditus, who had come to him from the Philippian church before falling ill (Philippians 2:25).

First, the Philippian Christians were warned about those Paul labels as "dogs." Unlike today's domesticated pets, dogs in first century Philippi were generally wild pack animals. They were aggressive scavengers and thieves, devouring whatever food they could find (Matthew 7:6; 15:26, 27; Mark 7:27, 28; Luke 16:21; 2 Peter 2:22; Revelation 22:15). False teachers, like those Paul will describe, are looking for their own interests. They are not truly part of the family of faith, but are seeking to take whatever they can get from others.

Second, the Philippians were warned against those who were actually doing evil: false teachers. This was a theme Paul also warned other groups of Christians about (2 Corinthians 11:13). One particular group Paul cautions against are the "Judaizers" (Titus 1:10). These were teachers who claimed that faith in Christ was not enough for salvation. These people added the requirements of the Old Testament law on top of the gospel. This focus on legalism turned the practice of circumcision from an act of obedience into a "mutilation" of the flesh.

In contrast, Paul refers to faith in Christ as the "true circumcision" in the next verse. These false teachers sought to promote adherence to the Torah as part of Christianity, something Paul spoke against. Salvation is by grace through faith in Christ (Ephesians 2:8–9), not by works, including works of the law.