Here's a passage from William Barclay's commentary on (what else) The Letter to the Philippians:
On the day when Christ comes it will be like the coming of a king. On such a day the king's subjects are bound to present him with gifts to makr their loyalty and to show their love. The only gift Jesus Christ desires from us is ourselves. So, then, a man's supreme tak is to make his life fit to offer to Him. Only the grace of God can enable us to do that.
I do not desire the fat of animals--the sacrifice I require is a rended, contrite heart.
Over and over gain we are told that the sacrifice acceptable to God is the sacrifice of a life lived with Him. Like any good parent, God desires not material things that we can "give" Him (because it all belongs to Him anyway), but our love. And our love is best demonstrated in living a life that reflects all that He has taught us of love.
He's not asking the impossible, merely the improbable. We can't do it, but He can, and His grace is both sufficient and efficient.
