Every faculty you have, your power of thinking or of moving your limbs from moment to moment, is given you by God.
If you devoted every moment of your whole life exclusively to His service you could not give Him anything that was not in a sense His own already.
So that when we talk of a man doing anything for God or giving anything to God,
I will tell you what it is really like.
It is like a small child going to its father and saying, “Daddy, give me sixpence to buy you a birthday present.” Of course, the father does, and he is pleased with the child’s present. It is all very nice
…but only an idiot would think that the father is sixpence to the good on the transaction.
When a man has made these two discoveries God can really get to work. It is after this that real life begins. The man is awake now. We can now go on to talk of Faith in the second sense.
(Mere Christianity Chapter 11, C.S. Lewis)