Therefore we are to “work out” the salvation we have (2:12). The word here, katergazesthe, has the sense of developing or elaborating something, bringing it to the fullness of what in its nature it is meant to be. But we do not do this as if the new life were simply our project.
WORD STUDY ON WORK OUT - DEVELOP OR ELABORATING SOMETHING, BRINING IT TO THE FULLNESS OF WHAT IN ITS NATURE IT IS MEANT TO BE

