If we're born again, we put off the old man and put on the new.
1. When a sinner receives the Holy Spirit, he also receives the New Birth, which means that he becomes a child of God.
2. The Holy Spirit "quickens" or brings to life the dead spirit of that person, and indwells that spirit. That is essentially "the new creature in Christ" who desires the things of God and delights to obey God and communicate with God. This is where God works in us both to will and to do of His good pleasure.
3. At the same time the flesh -- the old man -- has not been eradicated. Therefore every epistle exhorts the believer to walk in the Spirit and to mortify (or crucify, or deny) the flesh and its lusts.
4. There is always a battle between the flesh and the Spirit, but the Holy Spirit empowers the Christian to become an overcomer by faith and by resisting the Devil and mortifying the flesh. This means that the sin nature cannot dominate the true Christian, but by the same token Christians can and do sin, and must confess their sins, and repent.
5. We are commanded to renew our minds, which must move from the influence of the world and evil spirits to the influence of the Word and the Holy Spirit. This renewal comes by "the washing of the Word", meaning the reading, study, and application of Scripture to every situation and circumstance. Now if we look at this Scripture carefully, the non-conformance to the world and the renewal of our minds is our responsibility, and this is somehow being pushed aside in this discussion: (a) And be not conformed to this world: but (b) be ye transformed by (c) the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God.
That is how the mind is renewed progressively as the Christian is progressively sanctified. There is no "magic bullet" which suddenly makes sinners into saints. However they are positionally saints because the Holy Spirit dwells within then and seals them for the completion of their salvation.