Who gives believers victory over the old Adam?

Les explains that since conversion, Christ in the person of the Holy Spirit is dwelling within the believer. That inward man is where Christ now dwells, and He is the one who can give victory over our adversary, first and foremost, old Adam. Les notes that old Adam is under the control of Satan. There is a warfare between the new nature and the old, and Paul describes being brought into captivity to the fact of life that old Adam is in his members. Les points out that Paul has not yet mentioned the Holy Spirit’s power in the first seven chapters; it will break out in chapter 8. Paul cries, “Oh, wretched man that I am. Who shall deliver me from the body of this death... from this influence of old Adam? How am I going to overcome it?”