Renewing of the mind

"And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God." (Romans 12:2)

A closer look:
Renew - renovate.
Mind - intellect (distinguished from will and affection); can also refer to the inner man, or the spirit (distinguished from the body).

First and foremost, it is God's grace of Salvation that renews a man (similar to the idea of "born again" in John 3:3, 7 and Titus 3:5). Salvation transforms a sinner into a saint (consider Rom. 1:7; 2 Cor. 5:17; Eph. 2:8-10; 1 John 3:2). Second, Sanctification is the practical progress of God's renewing work in our lives. Our ultimate goal is to bring glory to God, and we learn how to do this every day as we read and study the Bible, pray, and live out the things which we have learned from God (see Luke 9:23; 2 Cor. 4:16; Eph. 4:23). We are aided by the Word and Holy Spirit. We are renewed when we get rid of our old mindset and posses or put in its place a godly mindset. How does change take place? By the renewing of the mind.