There are four different references to the rapture of the church in the book of Philippians. In Philippians 1:6 the reference is “the day of Christ Jesus.” In both Philippians 1:10 and 2:16 the reference is “the day of Christ.” Then in Philippians 3:20-21, the rapture reference is the entire discussion, “eagerly wait for a Savior, the Lord Jesus Christ; who will transform the body of our humble state into conformity with the body of His glory, by the exertion of the power that He has even to subject all things to Himself.” Here are each of those verses (in the NASB) followed by a short examination of each.
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.
Here, as Paul begins his letter to the Philippian church, he expresses his thanks to God for how good he felt toward them—indeed for how confident he was that their salvation was secure in Christ, and that it would be secure until “the day of Jesus Christ.” That day will be the day of the rapture, which will be the first phase of His coming.
This introduction is very similar to Paul’s introduction to the Corinthian church (1 Cor. 1:4-7), in that he expresses his confidence that they would be found blameless when He comes, hence, that God’s good work of grace would continue until He comes.
What a wonderful truth this is—that though we sin every day, His wonderful work of grace forgives us (those who believe) and keeps us blameless until we see Him face to face.
And this I pray, that your love may abound still more and more in real knowledge and all discernment, 10 so that you may approve the things that are excellent, in order to be sincere and blameless until the day of Christ.
In this verse, which is part of Paul’s prayer to the Philippians, the reference to the Lord’s coming, “the day of Christ,” is shorter than in verse 6, but it speaks of the same day—the day of the rapture.
Notice that Paul’s message here is no longer on their salvation—that it will be completed; rather, the message and prayer is that they would continue in the excellence of their works to the “glory and praise of God.” Hence, though Paul stressed in verse 6, that their salvation by God’s good work in them would definitely be completed, Paul now is saying that it is also important to live excellently and righteously in view of His return. Why? Not to confirm their salvation, but to praise Him and to please Him. Yes indeed, the Christian’s salvation is already confirmed and will be completed on the day of Jesus Christ. However, the way the Christian lives is not so confirmed. This is something he or she needs to continue to work at and pray about every day until He comes.
Holding fast the word of life, so that in the day of Christ I may have cause to glory because I did not run in vain nor toil in vain.
The reference here to the rapture, or the “day of Christ,” is the same as in Philippians 1:10. And like Philippians 1:10, the teaching is not (as Phil. 1:6) that we will be found complete in our salvation, but rather that we should do what is necessary to present ourselves as praiseworthy to Him on the day of His appearing.
And in this context, the “day of Christ” is not only the day of His coming for us; it also includes His judgement—the judgment of believers, where He will reward us for our lasting works. In that light, as the context indicates, we should be careful to do “all things without grumbling or disputing” in order to be “blameless and innocent” in this evil world, so to “appear as lights in the world, holding fast [or forth] the word of life…”
So this is the type of Christians we are to be when He comes. And if we are, then we will have a reason to rejoice when He comes, for it will mean that our life was not lived in vain. And it will also mean that He will be pleased with us for the fruit of our life.
For our citizenship is in heaven, from which also we eagerly wait for a Savior, the Lord Jesus Christ; 21 who will transform the body of our humble state into conformity with the body of His glory, by the exertion of the power that He has even to subject all things to Himself.
The clear theme of the context that Paul is bringing to the Philippians here, is that since their citizenship is in heaven they ought to walk having their minds set on heavenly things, following his example—and to also learn from other believers.
Then to magnify the thought of their heavenly citizenship, Paul reminded them that they should be eagerly waiting for their Savior, the Lord Jesus Christ, who will come for them.
And when He comes, as Paul tells us, He will transform (or change) our bodies into conformity with His body of glory. These verses are clearly speaking of the first phase of His coming, when He will first resurrect the dead believers in Christ, and then rapture all those who are alive (1 Thess. 4:16-17). And when He takes us up with Him (both the resurrected and the living), as they are coming out of their graves and going up in rapture, He will, by the exertion of His power, transform them. He will miraculously remake our bodies to be glorious like His body, which will be marvelously adapted for heaven (1 Cor. 15:51-53).