These verses summarize what must occur during the conversion process. The apostle Paul presents our marching orders directly. We are to sacrifice our bodies while we still live, that is, submit ourselves wholly to God and to His way of life, which is only reasonable, since having redeemed us, He owns us completely. In addition, we are to reject this world's attempts to pull us back into its ungodly lifestyles, despite its many allurements. Instead, we are to engage in the transformation of our minds into perfect alignment with God's will.
Paul calls it "the renewing of your mind." This renewing is not making the mind new in the sense of time. For instance, to say one has a new bike suggests that it was recently purchased; someone else has not used it. The renewal of Romans 12:2, however, speaks to quality. We might understand it better by using the terms "refresh," "revive," or "rejuvenate." When a tool—say, a chisel—is old and dull, a craftsman will renew it by cleaning off the rust, sharpening the edge, and perhaps putting on a new handle. Essentially, this is what God is doing in renewing our minds. He is taking an old, ill-used mind, cleaning it, sharpening it, and putting it to use in His work.
Consider that another spirit has had many years to shape our minds to follow his way (Ephesians 2:2; Revelation 12:9). Satan the Devil's way of life is that of pride, vanity, lust, greed, envy, deceit, murder, adultery, and covetousness—all the evil things that we are supposed to be putting off. While he had a hold on us, Satan impressed his ungodly way on our minds, but now God has called us and is now in us by His Spirit, transforming us, refreshing our minds, so that we can change the quality of our minds from carnal to spiritual. The transformation that we are undergoing will take us from the self-absorbed, degenerate, sensual mentality to the outgoing, pure righteousness of God's own mind.
The last part of Romans 12:2 can be paraphrased as "so that you may test or experience all the benefits of His will." Without His mind being formed in us through the Holy Spirit, we would have no way of truly understanding His will or His way. Our minds must be transformed so that we can have even the capacity to understand the differences between God's way and Satan's way, as well as the overwhelming benefits of living as God prescribes. Only then, as it says in Deuteronomy 30:19, can we truly "choose life." This process is happening in us so that we can make the choices that will allow us to live eternally.
