Here we have the comparison clearly between living for sin/'self' and living for God with the results of both.
First to the sinful man: "The mind" means what they are focussed on, their goals, their passions, their aims. Gill makes a parallel of it to the 'wisdom' of man and we know from 1 Corinthians 3:19 that "the wisdom of this world is foolishness in God's sight". Our sin (and as humans we have "all sinned and fallen short of the glory of God" - Romans 3:23) deserves only one thing: death. It is the result of it, it is the payment of it. Barnes says this: "it not only leads to death, or leads to misery, but that it is death itself; there is woe and condemnation in the very act and purpose of being supremely devoted to the corrupt passions, Its only tendency is condemnation and despair." Sin itself has the very goal of condemning us before God. What does Paul here mean by death? He cannot simply mean physical death because we know that all die - christians and non-christians no matter if we are forgiven by God or not. Paul means not only physical death but spiritual death. Sin is a direct attack on God, on his character and on who he is. He is good, sin is evil. He is perfect, and just, sin is wicked and corrupt. He is all wise, sin is rebellion against God and trying to live by our own 'wisdom'. He is all powerful, the creator of all things, sin is a denial of his right to rule over our lives. God is the just and perfect judge, and sin deserves his wrath for eternity - we can never ever have the full punishment for it. That is how bad sin is. So what is sin? Disobedience to God. Yep, one 'little' lie is bad enough to make us deserve eternal wrath in hell, and we've all done much worse then that.
But of course thats not the end of the story. In fact, thats the beginning. The point of the gospel is that Jesus is God, and he came to earth as man. He came and died in our place if we are christians - taking our sin, and God's wrath. He is God, so he could take it and the punishment for it. He humbly submitted himself to God and died in our place so we may be forgiven if we have faith in him - not just belief in him, but personal trust that he has saved us if we are his people. He then rose again, proving that he had fully dealt with sin - he had dealt with it, and he dealt with death which was the physical consequence of it here. What a might and gracious saviour!
"The mind controlled by the spirit". A quick point: Controlled = controlled. We are either slaves to sin (which leads to wrath) or slaves of God. If slaves of God we are so willingly, and it is an honour. He is a good master, his burden is easy and light. But we owe him all none the less. But what awesome Grace! We have the Holy Spirit in us! God living in us to help us, to encourage us, to grow us, to challenge us, to rebuke us and to strengthen us. Constantly with us. As I said before, "the mind" refers to what we are focussed on. As Christians we need to be focussed solely on God, on serving him - it should be joy to us to serve him and to give up sin. We were created to glorify God and through Jesus we can do that. As christians, if we have genuinely repented of our sin and turned to God, we will fight sin. How can we have God living in us yet keep disobeying him? Sure we stuff up, and there is forgiveness in Christ, but there needs to be a change in life once we are saved. How are you living? Does it match your faith?
And we have God constantly looking after us and caring for us, constantly helping us - the creator of the universe helping and caring for us! What's the result? Life and peace - Life as opposed to death. We were dead in our sin, now, through Jesus alone, we are alive in Christ! and we have the promise of eternal life in heaven as well after we die! Peace refers to a few things: peace of conscience - we have no guilt, there is complete forgiveness in Jesus. Peace from fear - we have God protecting us and nothing will ever happen to us that is out of his control. Peace of assurance - we know we will have eternal life with him at the end no matter how much we stuff up if we are genuinely his people. But most of all: Peace with God. We were his enemies, directly attacking him with our sins, yet in Jesus we are adopted as Children. From death to life, from condemnation to grace, from enemies to children of God, from a worthless existence outside of what God created us for to being able to serve him and live as he created us to. What a glorious saviour! What a marvelous creator!
Soli Deo Gloria!