In Paul’s letter to his Philippian brothers, he charged them to conduct themselves in a manner worthy of the Gospel, 1:27.  He defined worthiness first as unity, verse 27b "…with one mind striving together…"  Biblically, unity can be defined in the following ways: Collectively, as we accept our one humanity having sinned in Adam (Romans 5), and individually,  partaking of the same nature whereby we each sin willingly; also, one in a common salvation having been saved by God’s grace (1:7) and not of ourselves. 

Finally, we are one in purpose, which purpose is to defend and confirm the Gospel (1:7].  Militarily, once a battle has been fought and an area secured the land must then be defended from the enemy that will seek to take it back.  The context of verse 27 is to strive or fight together to defend the Gospel.  The primary battle won was at Jesus’ grave, where He proved His claims to deity when He rose victorious from the dead as a living sacrifice for sin.  

Every succeeding battle has been to to defend the Gospel truth that Jesus Christ is the only way of Salvation.  The battle is the Lord’s and the rules of engagement are His as well, our concern is to conduct ourselves in a manner worthy of His Gospel. Conduct (politeuomai) means to conduct one’s self according to the laws and customs of the state; no Christian has the right to tell the Gospel according to their own inclinations, feelings, or reasoning.

There are thousands of "churches" today that ignore the doctrine of sin in favor of “Jesus accepts you as you are;” they deny God’s pending judgment by telling people, “you are on a spiritual journey.” Furthermore, they avoid the internal consequences of sin such as spiritual blindness, hardness of heart, and rebellion towards God by emphasizing, “God has a wonderful plan for your life, or you are special in God’s sight.”

Of course, congeniality, kindness, and a loving spirit should always accompany Gospel truth, but it must be Gospel truth that is spoken. In reality, Jesus preached a Gospel of condemnation with a command to repent and believe for the forgiveness of sins. “You snakes, you offspring of vipers! How will you escape being condemned to hell?” Matthew 23:33 “Do not be afraid of those who kill the body but cannot kill the soul. Instead, fear the one who is able to destroy both soul and body in hell.” Matthew 10:28

Many more references could be added because when Jesus evangelized He spoke more of hell than He did of heaven.

According to Paul, good conduct is best exemplified by the preacher, who does not alter the message to make the people happy, but remains true to its original intent to please its author, who is God. Paul was an Apostle, among the first generation to proclaim the message of Jesus Christ, and in his words, “…I am appointed for the defense of the gospel” Philippians 1:16.

Lastly, in 1:27 Paul encourages them to, “fright together for the faith of the gospel,” emphasis on the definite article “the” because wherever the definite article appears before the word faith it refers to the body of truth contained in the Bible. For example, “and a great many of the priests were becoming obedient to the faith.” Acts 6:7, “But Elymas the magician (for so his name is translated) was opposing them, seeking to turn the proconsul away from the faith.” Acts 13:8, “Now while they were passing through the cities, they were delivering the decrees which had been decided upon by the apostles and elders who were in Jerusalem, for them to observe. So the churches were being strengthened in the faith, and were increasing in number daily.” Acts 16:4-5, etc.

Every generation of Christians since Christ rose from the dead has been responsible to defend the Gospel message, for by it alone God has chosen to save sinners from eternal destruction.

In the Christian life, good conduct is not just a matter of good behavior, but of good teaching!