Php 1:6-7, 6 And I am sure of this, that he who began a good work in you will bring it to completion at the day of Jesus Christ. 7 It is right for me to feel this way about you all, because I hold you in my heart, for you are all partakers with me of grace, both in my imprisonment and in the defense and confirmation of the gospel.
Paul was convinced of God’s power in saving (He who began a good work in you) and keeping (will complete it at the end, Jude 1:24). His confidence as he notes was solely on someone greater than himself. In Rom 1:16, he states why he was not shamed of the gospel, for it is God’s POWER unto salvation. We can trace this back to Jesus’ words in John 6:29,… “This is the work of God, that you believe in Him whom He sent.”
This expression stemmed from the heart he had for them even as prisoner. They were partakers of the grace of God given to them. The grace of God unified them, equipping them to live the Christian life, both in endurance of suffering, defending and in propagating the gospel. Grace that warms the heart unifies believers to have affection for one another as we see with Paul to the Philippians, this is God working.