Christians make up a unique family. Christians have one Father — God. Christians have one Saviour - Jesus Christ. Christians are directed through the work of the indwelling Holy Spirit and the 
Word of God.
In verse 12 Paul wrote with that sense of endearment that sets true saints apart from the lost. It is possible for saints to get in the flesh and try to destroy what God is building. It is a very poor testimony when that happens. It is good when those saints who are in sin repent and get right with God and work together with the mind of Christ.
Paul encouraged these saints with the testimony that they had. They understood the importance of the apostles. Jesus Christ chose twelve apostles. Judas Iscariot rejected Jesus’ authority and he betrayed Jesus Christ and then went out and hung himself. Jesus Christ later chose the apostle Paul as the twelfth apostle. There are no more apostles after that time. The apostles were each chosen by Jesus Christ personally and they had to have seen Jesus Christ in the flesh. No one can make that claim today. There are many false apostles, but there are no true apostles today.
Paul noted the saints had obeyed him. They had listened to him and they were blessed in following his teaching. We have already noted that Paul was not a self-made man. He was chosen by the Lord Jesus Christ and he demonstrated his faithfulness to the Lord. Obedience does not happen under coercion.
Every good parent wants their child(ren) to obey them whether they as parents are present or if they have given instructions and then left. Paul praised the Philippian saints with their obedience to him even in his absence.
Paul ended verse 12 with the exhortation to “work out your own salvation with fear and trembling.” Notice that he did not tell them to work “for their salvation”. He was speaking to saints. They were already saved. Every true Christian needs to live out their salvation in accordance with God’s Word. That is where the fear and trembling comes in. There is a sense of reverence and awe toward God. The true child of God does not want to offend his Saviour and Lord. He has that sense of holy respect for God. He wants to be a pure and shining light for the Lord.
This is important for true Christians to keep in mind today. There is such a smorgasbord of “Christians” today that it creates great confusion for the lost. Too often those who are saved are more concerned about their own feelings and opinions, than they are in submitting to the Lord. This was not the case in Philippi, but Paul was directed by God to warn them of that danger.
In verse 13 Paul reminded them that even though he had praised them for obeying him, it was God Who was working in them both to will and to do His good pleasure. That is why Paul could say: “I can do all things through Christ which strengtheneth me”. God is so good. He saves repentant sinners. He then equips those who are saved to be able to do what He expects of them. He gives them His Holy Spirit to guide and direct them into all truth. He gives them a new desire and the ability to obey Him. It is evident that God is not pleased with the great confusion among professing Christians today. There is no justification for this. As we have mentioned in other devotionals, Jesus Christ addressed seven different local churches in the book of the Revelation. He rebuked most and challenged them to get back to His Word. That is what is still needed today. When God’s Word has Its’ rightful place in the saints’ lives, things will function according to God’s will.
Those who are saved all have the same Holy Spirit indwelling them. The Holy Spirit is working inside the true saint to bring them to likemindedness in Christ.

I Corinthians 1:13 Is Christ divided? was Paul crucified for you? or were ye baptized in the name of Paul?

The divisions we see today are not pleasing to the Lord. The compromises we see today are also not pleasing to the Lord. We have seen already that humility is essential among the saints. We need to submit to God first of all. When that is in place, then submission to those that God places over us will not be difficult. When God does not have His rightful place in our hearts, then nothing else will work either.
Notice in verse 13 that saints work for God’s good pleasure. Saints want God to be pleased with them. They want to know that they are doing that which He requires. God’s will is never an interference to true saints. It is an interference to the lost and to the carnal Christian. They will find serving Him faithfully an inconvenience. They will try to “squeeze” God into their plans, rather than giving Him first place in their lives.
In verse 14 we see that there should be no murmurings or disputing among God’s people. Paul had to name names at times. He mentioned those who were fighting against the truth. They did not like what he said, and they tried to keep others from following him. The saints at Philippi needed to stay away from that attitude. They needed to keep the mind of Christ in focus at all times.
In verse 15 the challenge is to be blameless and harmless. That is a tall order that is impossible in the flesh. However, because God equips the saints, it is possible and it is required. We need to behave as sons of God. Notice we are not sons of God in the Mormon sense. We do not become little gods who do not sin, etc. We are made sons of God at the moment of salvation.

John 1:12 But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name:
13 Which were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God.

That is the blessed reality of those who are truly saved. We need to remember that we do not define what a son of God looks like. God defines that for us in His Word. We have already looked at some of that in this letter.
The saints need to be without rebuke. It is nice to not be condemned. Paul wrote about this in Romans 8.

Romans 8:1 There is therefore now no condemnation to them which are in Christ Jesus, who walk not after the flesh, but after the Spirit.
2 For the law of the Spirit of life in Christ Jesus hath made me free from the law of sin and death.