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; 11 having been filled with the fruit of righteousness which comes through Jesus Christ, to the glory and praise of God. (NASB, bold for emphasis)
In Philippians 1:10, 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—“the day of Christ Jesus.” 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.