I thank my God in all my remembrance of you, 4 always offering prayer with joy in my every prayer for you all, 5 in view of your participation in the gospel from the first day until now. 6 For I am confident of this very thing, that He who began a good work in you will perfect it until the day of Christ Jesus.

– Philippians 1:3-6 (NASB)

The very phrase (here in Phil. 1:5) “from the first day until the present” stresses perseverance in spite of all obstacles. The prayers, the sympathies, the testimonies, the willingness to make a pecuniary contribution, all these had never ceased. The Philippians had not lost their first love (contrast Rev. 2:4) during this entire decade.

Paul thanks God for this, for it was God who had grafted his own image in the hearts of the Philippians. hence, to the immediate reason for the thanksgiving the apostle now adds the ultimate reason: being confident of this very thing that he who began a good work in you will carry it on towards completion. Note how closely the apostle links human perseverance (your fellowship in the gospel from the first day until the present”) with divine preservation (“he who began a good work in you will carry it on toward completion”). Any doctrine of salvation which does not do full justice to both these elements is unscriptural. See phil. 2:12, 13; II Thess. 2:13. Although it is true that God brings his work to completion, it is equally true that when God has once begun his work in men, the latter by no means remain merely passive instruments!

The good work which God had begun within the hearts and lives of the Philippians was that of grace, whereby they had been transformed. This work, indeed, was good in origin, quality, purpose and result. The result had been their own willing and working for god’s good pleasure (Phil. 2:12, 13); specifically, their own hearty co-operation in whatever pertained to the gospel.

Now Paul is confident that God will not permit his good work of transforming and qualifying grace to remain unfinished. The expression “will carry it onward toward completion” implies “and will present it complete.”

Accordingly, out of the darkness and distress of a prison in Rome a message of cheer reaches each Philippian believer, enabling him to say:

“The work thou hast in me begun
shall by thy grace be fully done.”

God, accordingly, is not like men. Men conduct experiments, but God carries out a plan. God never does anything by halves. Men often do.

This teaching of divine preservation for a life of service (hence, with implied human perseverance) is in harmony with that of the entire Bible, which tells us about:

• a faithfulness that will never be removed (Ps. 89:33; 138) ,
• a life that will never end (John 3:16)
• a spring of water that will never cease to bubble up within the one who drinks of it (John 4:14)
• a gift that will never be lost (John 6:37, 39)
• a hand out of which the Good Shepherd’s sheep will never be snatched (John 10:28)
• a chain that will never be broken (Rom. 8:29, 30)
• a love from which we shall never be separated (Rom. 8:39)
• a calling that will never be revoked (Rom. 11:29)
• a foundation that will never be destroyed (II Tim. 2:19)
• and an inheritance that will never fade out (I Peter 1:4, 5).

It should be stressed, however, that according to the present context (and all of Scripture) this preservation is not for a purely selfish purpose but is for service. God’s work of grace qualifies men for work.

Now God will carry his good work on toward completion until, and will actually have it all completed on, the day of Christ Jesus. This day is also called:

• the day of Christ (Phil. 1:10; 2:16)
• the day of our Lord Jesus (Christ) (I Cor. 1:8; cf. II Cor. 1:14)
• the day of the Lord (I Thess. 5:2) II Thess. 2:2) cf. I Cor. 5:5)
• the day (I Thess. 5:4)
• the parousia (of the Lord, of our lord Jesus, etc.) (I Thess. 2:19; 3:13; 4:15; 5:23; II Thess. 2:1, 8; cf. I Cor. 15:23; etc.).

It is called the day of Christ Jesus because on that day He will be manifest in glory, will be met by Hid bride (the church), will judge, and will thus be publically vindicated.

- William Hendriksen, commenting on Philippians 1, BNTC