Paul and his spiritual son Timothy (1 Cor. 4:17; etc.) were behind this epistle. It could not be more clear that these words were written to saints (Christians). This church started primarily with just two families: Lydia and her household who got saved and the Philippian jailer and his family who also got saved (Acts 16:13-34). That was on Paul's second missionary journey. This important church group of first-century Christianity began from a mission visit because of a vision Paul had:
During the night Paul had a vision of a man of Macedonia standing and begging him, “Come over to Macedonia and help us.” After Paul had seen the vision, we got ready at once to leave for Macedonia, concluding that God had called us to preach the gospel to them. From Troas we put out to sea and sailed straight for Samothrace, and the next day on to Neapolis. From there we traveled to Philippi, a Roman colony and the leading city of that district of Macedonia. And we stayed there several days. (Acts 16:9-12)
It was a leading city, but only two families came to salvation. This was the first church group to financially support Paul in spreading the vital message:
Phil. 1:6 is a primary support passage used by the eternal security people, but severely taken out of its context. It was their partnership in the gospel (their financial giving) that Paul wrote about. That was the work that God began in them and that would be carried on to completion. Their financial giving is again mentioned in chapter 4:
Moreover, as you Philippians know, in the early days of your acquaintance with the gospel, when I set out from Macedonia, not one church shared with me in the matter of giving and receiving, except you only; for even when I was in Thessalonica, you sent me aid again and again when I was in need. Not that I am looking for a gift, but I am looking for what may be credited to your account. I have received full payment and even more; I am amply supplied, now that I have received from Epaphroditus the gifts you sent. They are a fragrant offering, an acceptable sacrifice, pleasing to God. And my God will meet all your needs according to his glorious riches in Christ Jesus. (Phil 4:15-19)
Hence, the once saved always saved people have distorted Phil. 1:6 (as they have many other Scriptures) for support of their false grace message.
Phil. 1:7 states that Paul defended and confirmed the gospel. Virtually everything Paul did can be related in one way or another to the gospel itself.
Paul had a true love and concern for those saints. That love manifested in warnings about false teachers (Phil. 3:2); the need to be careful, even in what thoughts are pondered (Phil 4:8); etc.
Have you ever wondered how Paul prayed? There, in part, is the answer. He especially prayed for their love to increase in knowledge and insight. This is the kind of prayer to pray for your converts.
Paul was in prison and in chains at the writing of this epistle and could have been very discouraged as the devil surely tried to get him to be, but he wasn't. He looked on the bright side, even regarding his own imprisonment and the spread of the gospel message itself. He believed the gospel was still being advanced and that was great. (Paul being dead to his own comforts and well-being is reflected here.)
In Rome, where Paul was in prison, Christians were speaking God's word in a courageous and fearless manner, which is the way it should always be spoken, since it is absolute truth. See Eph. 6:19,20.
The motive of some preachers was not pure. Such existed even in Paul's day. Those preaching out of envy and rivalry (or selfish ambition) were actually trying to stir up trouble for Paul. Imagine that! They wanted Paul to get in more trouble than he was already in and preached to bring that about. Shocking! Envy and jealousy are capable of terrible things including murder, according to other Scriptures. Not everything that appears to be godly is out of good motive.
NOTE: Just because some preachers are not as they should be doesn't mean all preachers are like that. The motive of other preachers was goodwill and love. God will bring all such things to light at the judgment:
Therefore judge nothing before the appointed time; wait till the Lord comes. He will bring to light what is hidden in darkness and will expose the motives of men's hearts. At that time each will receive his praise from God. (1 Cor 4:5)
Hence, examine your motives now and change accordingly!
Paul had no concern about his own personal health and well-being. His primary goal was to spread the plan of salvation (gospel) so others could be saved. See 2 Tim. 2:10 and 1 Cor. 10:33.
The importance of prayer and helping one another this way is shown here. (The Philippian Christians prayed for Paul besides helping him financially. The early church knew the vital necessity of prayer to God.)
It takes courage to be a Christian, which is exactly the opposite of how the world tends to portray a Christian. Paul wanted Christ to be exalted through him and that is the way it had been since his conversion to Christianity. Ponder this related Scripture about courage:
But Christ is faithful as a son over God's house. And we are his house, if we hold on to our courage and the hope of which we boast. (Heb 3:6)
Notice the cited conditions for a Christian to remain God's house. (Heb. 3:6 refutes eternal security too.)
Paul clearly wanted all to know that his purpose to live was for Christ. That meant living holy and preaching God's truth, even though he would sometimes suffer great need and often be in harm's way.
Paul actually looked forward to his own physical death, as should everyone who is also living for Christ. Paul knew for the righteous, physical death is gain and better by far. [Remember, Paul was caught up to heaven (2 Cor. 12:2-4), but it is not clear if that was before or after this epistle.]
Physical death is also mentioned here as a mere departure, that is, as taking a trip. When a person dies his spirit leaves his body (James 2:26) and he goes home—either to be with Christ if righteous or to fiery torment if unrighteous.
To be around someone like Paul would be a major spiritual advantage for the righteous. His godly consistent example would help Christians grow spiritually in various ways. Paul's presence would also make those Christians joyful.
Paul wrote whatever happens, referring to the many uncertainties of this life, even for the faithful. In other words, regardless how bad it might get make sure your conduct is holy and worthy of the gospel. That whole church group (both men and women) was to be like one unit reasoning for the faith of the gospel without fear. For them to serve God in a fearless manner would be a double sign—to the unsaved that they will be destroyed (which doesn't mean annhilated), but for the faithful that they would be saved, that is, enter God's kingdom after death. (Paul certainly didn't believe in Universalism—the false doctrine that all will get salvation.) Suffering for the cause of Christ goes with believing on Jesus and having salvation.