I'm new here-so it's none of my business-I am working out my own salvation with fear and trembling.
Shalom
J.
In context;
Philippians 2:5 Let this mind be in you, which was also in Christ Jesus: 6 Who, being in the form of God, thought it not robbery to be equal with God: 7 But made himself of no reputation, and took upon him the form of a servant, and was made in the likeness of men: 8 And being found in fashion as a man, he humbled himself, and became obedient unto death, even the death of the cross. 9 Wherefore God also hath highly exalted him, and given him a name which is above every name: 10 That at the name of Jesus every knee should bow, of things in heaven, and things in earth, and things under the earth; 11 And that every tongue should confess that Jesus Christ is Lord, to the glory of God the Father.
12 Wherefore, my beloved, as ye have always obeyed, not as in my presence only, but now much more in my absence, work out your own salvation with fear and trembling. 13 For it is God which worketh in you both to will and to do of his good pleasure.
I believe the former part of verse 12 was about the obeying having that mind of Christ in worship for how we are to honor the Father by which is by only honoring the Son in glorifying the Son and by Him, God the Father.
The latter part of that verse per your quote is in regards to the verse 13 about Who is working in you which is the Lord Jesus Christ.
Philippians 1:
6 Being confident of this very thing, that he which hath begun a good work in you will perform it until the day of Jesus Christ: 7 Even as it is meet for me to think this of you all, because I have you in my heart; inasmuch as both in my bonds, and in the defence and confirmation of the gospel, ye all are partakers of my grace. 8 For God is my record, how greatly I long after you all in the bowels of Jesus Christ. 9 And this I pray, that your love may abound yet more and more in knowledge and in all judgment; 10 That ye may approve things that are excellent;
that ye may be sincere and without offence till the day of Christ. 11 Being filled with the fruits of righteousness, which are by Jesus Christ, unto the glory and praise of God.
When we are to work out our salvation with fear and much trembling, we are not to resort to our own power as if we are working for that salvation hence with fear & much trembling as there is hardly any will power or boast in the religious flesh of our own towards that end, but that we respect what He has done in that we are saved by the grace of God and by faith in Jesus Christ and we can trust Him to do His work in us in helping us lay aside every weight & sin daily in walking in the light in fellowship with the Father & the Son every day.