The verse you referenced is NOT addressing the Salvation gift we have already been given.. of eternal life thru Christ....as we are sealed by His Spirit and fully and completely His as believers. ....
.....Rather,... Paul was addressing the Phillipian believers 'as a whole' for they had been bickering and arguing publicly.... his direction was to avoid giving in to the temptations of sinning, ....."Be careful in your corporate witness in Philippi. All of you work out before the whole town the being delivered or preserved or rescued each day from the sin of backbiting," (Phil. 2:13).
Philippians 2:12 cannot be a command to an individual church member telling him that he must work to escape hell. ....The reasons why?
..... In Verse 13 the word "beloved" is plural
.....the verb "have obeyed" is plural
... the verb "work out" is also in the plural
..... and the word "own" is plural.....
Thus, Paul is not giving a command to an individual, but is giving a command, a corporate command, to all the Philippian Christians ......He is commanding them 'as a group 'to do something -- watch closely their public behavior as a group.
How are the Philippians to do this?...
Verse 13:.... "For it is God who worketh in you" -- once again "you" is plural, ....referring to the entire group..... Since Christ has worked out the salvation from hell,... Christians need to work together to give as good a witness as possible to a lost world.
(Exerts from the Watchman)
Excellent..This was an exhortation for the need of the church to work OUT THEIR SALVATION ( an accomplished fact)