You're in the Fight of Your Life against Sin
Thinking about Romans 6:12.
Therefore do not let sin reign in your mortal body, that you should obey it in its lusts. (Romans 6:12)
When you are buried with Christ in baptism, you are set free from sin (Romans 6:3-7).
As Paul continues showing that the gospel of Christ does not encourage more sinning to get more grace (Romans 6:1-2), he turns his attention to the Christian’s ongoing fight against sin.
Don’t let sin get back on the throne.
Paul commands Christians not to “let sin reign” in their mortal bodies. They have been buried with Christ, died to sin, and now live unto God. Sin has been de-throned - sin no longer has “dominion” over them (Romans 6:14).
Christians have changed masters. Now, we are in the fight of our lives to keep sin off the throne.
Since we have died to sin, we must not let it keep on dominating our lives as before. The mastery and dominion of sin in our lives ended when we were baptized. Now the fight is to keep sin from capturing us again. - Pollard, Truth for Today Commentary, 213
Christians are God’s “workmanship, created in Christ Jesus for good works, which God prepared beforehand that we should walk in them” (Ephesians 2:10).
Don’t allow sin the upper hand over your body.
God is now on the throne of your life, not sin. Christians must not allow sin to have control of them once again.
The body is the arena of lust and temptation, and the choice is either to serve God or give in to the mastery of sin and become its slave. - Pollard, Truth for Today Commentary, 213
As Christians, we belong to God now. Our body is His and should be used for His glory.
Flee sexual immorality. Every sin that a man does is outside the body, but he who commits sexual immorality sins against his own body. Or do you not know that your body is the temple of the Holy Spirit who is in you, whom you have from God, and you are not your own? For you were bought at a price; therefore glorify God in your body and in your spirit, which are God’s. (1 Corinthians 6:18-20)
God will certainly help us in our fight against temptation and sin. Jesus Christ is our High Priest at the throne of God who understands our weaknesses to temptation and allows us to approach God for mercy with confidence (Hebrews 4:14-16). He is our Advocate with the Father (1 John 2:1-2).
However, we are responsible for "resisting” our adversary, the devil (1 Peter 5:8-9). God commands us not to “let” sin back on the throne of our mortal body.
We must show up to fight against sin.