It is forgiveness that sets a man working for God. He does not work in order to be forgiven, but because he has been forgiven, and the consciousness of his sin being pardoned makes him long for its entire removal than ever he did before. An unforgiven man cannot work. He has not the will, nor the power, nor the liberty. He is in chains. Israel in Egypt could not serve Jehovah. "Let my people go, that they may serve Me." was God's message to Pharaoh (exodus 8:1) first liberty, then service.