He did not say work out to assure your salvation........or ...work out to be saved....
He said they were to work out what they already had.. their salvation ...For it is God that works out His will in you ... for His pleasure ..(Phil2:12)
God does not work IN those that are not saved ...
False, this is what he wrote, except you reject the Authorized Protestant version of events. 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. For it is God which worketh in you both to will and to do of his good pleasure.
Phillipians, Catholic chapter two, Protestant verses twelve to thirteen,
as authorized, but not authored, by King James