the "wherefore" there in v. 12 indicates this is not a 'standalone' phrase but a conclusion reached by the preceding argument.
we need to look back at the preceding verses for the whole thought:
Let this mind be in you, which was also in Christ Jesus:
Who, being in the form of God, thought it not robbery to be equal with God:
But made himself of no reputation, and took upon him the form of a servant, and was made in the likeness of men:
And being found in fashion as a man, he humbled himself, and became obedient unto death, even the death of the cross.
Wherefore God also hath highly exalted him, and given him a name which is above every name:
That at the name of Jesus every knee should bow, of things in heaven, and things in earth, and things under the earth;
And that every tongue should confess that Jesus Christ is Lord, to the glory of God the Father.
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.
(Philippians 2:5-13)
so Christ set aside His glory and humbled Himself, taking on the form of a servant among us, in order that the great glory of His grace could be shown to us.
likewise, (wherefore!) we ought also to humble ourselves, having received this hope and promise of salvation by grace. yes, there is no more condemnation for us in Christ, and the penalty has been paid, and He has put in us a spirit of adoption and glory -- but it is God working in us, not us achieving righteousness, and our righteousness is by faith, a gift, not by our own strength and goodness -- so in respect, fear and humility we should do the things that are worthy of the high place He has set us in, the same way that Christ, though worthy to be glorified above all of the world, instead of seeking His own honor made Himself lower than all.
the Lord has given us backstage passes to the kingdom of heaven -- while we were lawbreakers with no right even to step foot in the parking lot.
should we cut line, jump on the stage, and disregard all the bouncers because we've been honored?
or meekly get in the back of the line, trying not to draw any attention to ourselves, being careful not to disobey any of the rules for fear that this awesome prize will be taken away?
this is admonishing us to be meek, to remember that the great things God has for us, and does in us, are not because we deserve honor, but because He loves us and is showing great mercy to us.
