A detail that Paul stresses here about living worthy of the gospel of Christ is that it requires unity. Twice, he speaks of unity: they are to stand firm in one spirit and they are to strive side by side with one mind. The reference to ‘spirit’ may be to the Holy Spirit, although some commentators argue that it refers to the human spirit because of the parallelism to the human mind in the next clause. In any case, the Holy Spirit is at work within believers in order to bring about unity.
The call to unity is illustrated in the images that the apostle uses. First, he charges his readers to stand firm, which is a military metaphor. He has in mind a group of soldiers engaged in a battle and resisting the enemy. They resist by not moving their ground. As long as they stand together they will be secure. Second, he also says that they strive side by side, which seems to be an athletic metaphor, perhaps taken from the Greek games in which teams of gladiators fought each other.
There are obvious lessons from this call to unity. First, worthy living cannot be done in isolation. A Christian cannot maintain this lifestyle by becoming a monk or its Protestant equivalent. Some people imagine that if they spend all their time by themselves they will be unpolluted and somehow live a worthy life. They will not achieve a worthy life by separating themselves from others of the Lord’s people.
Second, worthy living is not achieved by division. If we take Paul’s word pictures, what would happen if the group of soldiers started to fight each other or if the team did not work for each other? They would fail to achieve the purpose of their existence; even worse, they would be to blame for not achieving it. Worthy living for the gospel is only attained and maintained by living together as citizens of heaven.
The illustrations also give other insights regarding living worthy of the gospel of Christ. I suppose the imagery of the soldiers standing firm depicts the necessity of defending the gospel when it is attacked. The imagery of the athletes as they try to win the game may illustrate the necessity of adopting our tactics for winning from the details of the gospel. In any case, it is evident that what is central to unity is the content of the gospel. By gospel, Paul means the doctrines of the Bible. He does not mean the lowest common denominator possible – that is not the unity described here.
This unity is not merely an outward conformity. When Paul says that they should strive with one mind, he is referring to their inner attitudes. He does not only mean their intellectual commitment to unity, he also includes their emotional commitment and their volitional commitment. Each person in the Philippian church needed to have this inner commitment of love to one another in order for there to be true unity. Paul refers to such an attitude in Romans 15:5-6: ‘May the God of endurance and encouragement grant you to live in such harmony with one another, in accord with Christ Jesus, that together you may with one voice glorify the God and Father of our Lord Jesus Christ.’
Sadly, it is common to find people adhering around a set of beliefs and yet to have little love for one another. When such a situation happens, even although they may be able to sign the same doctrinal statement, they are not engaging in true unity. In true unity, there is a strong emotional bond of love between all the members of the church.
This is what it means to live a life worthy of the gospel. There is a rejection of isolationism and divisiveness, there is a commitment to the truth of the gospel, and there is a desire to serve with and for one another because there is the bond of love between them.