Jesus declared:

Matthew 6:24 No man can serve two masters: for either he will hate the one, and love the other; or else he will hold to the one, and despise the other. Ye cannot serve God and mammon.

In verse 5 of our text Paul was directed by God to remind the readers that the person that is after the flesh will live in sin. That is the nature of the flesh. You cannot expect right behaviour from someone who is lost. That does not mean we should accept bad behaviour, but we need to understand that lost people will live like lost people.
By contrast, those who are after the Spirit mind the things of the Spirit. Saved people will behave like saved people. It should be clear to all, that the Bible does not support the false teaching that some saved people will just never get past their “addictions”. That false teaching has no support from the Bible. That false teaching enables lost sinners to keep sinning and assuming they are going to heaven when they die. Not only that, but that false teaching is very damaging to the many who are observing what professing Christians are doing. There are many people who think they are going to heaven when they die, in spite of the fact that they have no testimony of Biblical salvation.
To suggest that you believe in Jesus is hardly grounds to claim you are saved. To suggest that you were baptized is also hardly grounds to claim you are saved. The fruit of the Spirit needs to be there in the saved person’s life.
In verse 6 Paul further stated: “to be carnally minded is death.” Paul was directed by God to address the carnality in the church in Corinth. God was not going to allow that to continue. He warned the offenders in very strong terms. In chapter 5 Paul was told to warn that church to turn the man living in sin, over to the devil. The church there was guilty of harbouring sin. God pronounced His judgment on the man and on the church. The good news is that they all listened to what God had to say. The defiant member repented and was forgiven, and the church acted on God’s warnings.
Back in our text, in verse 6 we see that “to be spiritually minded is life and peace.” You cannot have life and peace if you are not spiritually minded. A person can protest that fact all they want. God is always right. The person that is truly saved will enjoy God’s gift of eternal life and will know the peace of God in their heart. They will not avoid the truth, but rather will seek the truth.
In verse 7 we see further that the carnal mind is enmity against God. The Greek word translated as “enmity” means hostile, opposition”. It is contrary to the new nature for a true child of God to be opposed to God’s will.
Paul further stated that the carnal mind “is not subject to the law of God, neither indeed can be.” We have mentioned that above already. It is impossible for the lost person to be able to follow God’s law of righteousness. It is not possible for a lost person to be holy as Peter was directed to write.
In verse 8 Paul drew the conclusion. Those who are in the flesh cannot please God. Try as they may, they cannot do it. Of course the lost person will not try that hard. They may claim they are, but they do not have the capacity to try hard. Their best effort will be a half-hearted effort at best. They have a selfish motive in all that they do. The saved person wants to see others know God’s peace and blessing.
In verse 9 Paul was directed to challenge his readers. You notice where the “period’ is in that verse. We have the phrase: “But ye are not in the flesh,”. There is a comma after that phrase. That is an incomplete statement. Then we have “but in the Spirit,”. There is a comma after that phrase as well. Then we have the last phrase which is essential to the right understanding of what Paul wrote in this verse. “If so be that the Spirit of God dwell in you.” It is after that phrase that we see the period. This phrase completes the statement. God never gives a false hope to anyone.
The New Evangelical crowd would like a period after the first and second phrase in that verse. They do not want people to think too hard about life. They claim it is “legalism” to teach that God requires right actions of His children. It is important to listen to what God says and to reject the enablers.
The final statement of verse 9 is also very important. The Charismatics claim that you need to seek the “baptism of the Holy Spirit”. The ALPHA program teaches a distortion of the work of the Holy Spirit. There are countless numbers of people who have taken that course and are worse off afterward than they were before. Now they walk around with a false hope, based on the lies of some smooth talker. Before they were seeking and looking for something, but now they have been given a lie to hang on to. They may have had an experience and that is all they think they need. The good news is that some of those people will get saved because they will realize that the false teaching they received did not satisfy their soul, and they listened to the true Holy Spirit as He was convicting them of sin and drawing them to the truth.
The Holy Spirit is on the outside working on the lost person. However, He is on the inside working on the saved person. You notice in verse 9 that He is called “the Spirit of Christ.” The Bible makes is abundantly clear that the Godhead consists of God the Father, God the Son and God the Holy Spirit. They cannot be divided. They are One. The Holy Spirit indwells every true believer from the moment of salvation. If a person does not have the Holy Spirit within, that person is not saved. That is what God says.
In verse 10 we have a further conclusion. If Christ be in you, the body is dead because of sin. This again takes us back to chapter 7 where Paul talked of the members of his body warring against the law of his mind as a saved person. The body is dead because of sin. The body desires to be pampered. The body of man is also going to die and be buried. It is due to Adam’s sin, that the body dies. Death has two parts. There is the death of the body and there can be the death of the spirit. The death of the spirit is not the end of existence, but as God tells us, it is being cast into the lake of fire.
By contrast, the Spirit is life because of righteousness. The Holy Spirit is the third person of the Godhead and He is God and He is alive. He gives life to the saved person. The saved person does not live according to the flesh.

Ephesians 2:1 And you hath he quickened, who were dead in trespasses and sins;