The Philippian Christians were facing difficulties on two fronts. They were living in a city known for its coarseness and hostility to the Gospel. They were also having inner conflicts which threatened their very existence. False teachers were a threat to the Gospel (3:17-19), and disagreements among believers were a threat to their testimony in a hostile world. The secret to the "peace of God" (4:7) from the "God of peace" (4:9) is determined by how one thinks.