The compound is significant, indicating an accomplished fact. Through the various operations of His Spirit and the processes of His discipline, God has worked us out (Stanley, worked up) for this change. The process includes the dissolution of what is mortal no less than the renewal. The one is a step to the other. See 1Co 15:36.
Earnest of the Spirit
See on 2Co 1:22, and compare Rom 8:11. Of the Spirit is appositional, the Spirit as the earnest.