So then, my beloved, just as you have always obeyed, not as in my presence only, but now much more in my absence, work out your salvation with fear and trembling; for it is God who is at work in you, both to will and to work for His good pleasure -- Philippians 2:12-13
Indeed, which contextually is addressed to those who presently have their communion in Heaven (where they are made to sit with Christ, and have direct access into the holy of holies by the blood of Christ), and who thus are to work out (katergazomai) that salvation which they already have, to continue in that faith, to perform it, as Paul himself did. And the same Philippians who were told by Paul, I am in a strait betwixt two, having a desire to depart, and to be with Christ; which is far better, (Philippians 1:23; cf. 2Co. 5:8) though Paul himself testified to them that he "had not arrived," he earnestly sought "the high calling of God in Christ Jesus," to be perfect as he could be as those in the resurrection will be. (Phil. 3:10 But which resurrection is the only transformative event after this life that Paul manifestly teaches for the believer, and in which one will become like Christ.
For our conversation is in heaven; from whence also we look for the Saviour, the Lord Jesus Christ: Who shall change our vile body, that it may be fashioned like unto his glorious body, according to the working whereby he is able even to subdue all things unto himself. (Philippians 3:20-21)
But this man, after he had offered one sacrifice for sins for ever, sat down on the right hand of God; From henceforth expecting till his enemies be made his footstool. For by one offering he hath perfected for ever them that are sanctified. (Hebrews 10:12-14)
Now where remission of these is, there is no more offering for sin. Having therefore, brethren, boldness to enter into the holiest by the blood of Jesus, By a new and living way, which he hath consecrated for us, through the veil, that is to say, his flesh; And having an high priest over the house of God; Let us draw near with a true heart in full assurance of faith, having our hearts sprinkled from an evil conscience, and our bodies washed with pure water. (Hebrews 10:18-22)
Beloved, now are we the sons of God, and it doth not yet appear what we shall be: but we know that, when he shall appear, we shall be like him; for we shall see him as he is. And every man that hath this hope in him purifieth himself, even as he is pure. (1 John 3:2-3)
These things have I written unto you that believe on the name of the Son of God; that ye may know that ye have eternal life, and that ye may believe on the name of the Son of God. (1 John 5:13)
Thus the true believer presently has salvation, and positionally is in Heaven and will be with the Lord at death or His return, but is exhorted to continue in the faith, to live out his faith, and is warned against falling away in unbelief and what it effects. (Gal. 5:1-4; Heb. 3;6-14; 10;19-39) And it is this life with its trials and temptations that faith is proved, and character developed, thus even Christ was made "perfect" (as being tempted in all points as we are, yet without sin: Heb. 2:10,18; 4:15). But with the only transformative event after this life being that of the resurrection, which is when this vile body shall be changed, and be subdued to Christ, "Because the carnal mind is enmity against God: for it is not subject to the law of God, neither indeed can be." (Romans 8:7)
But a mark of saving faith is to continue in the faith and realize final full salvation, with the holy desire to be, as much as one can be, like Christ, because he was apprehended by Him to ultimately be so, and has already been made accepted by God in Him, being "bought with a price," (1Co. 6:20) no less than His sinless shed blood. Thanks to be God.