Our union with Jesus Christ is explained in Romans 6. It is expressed throughout the New Testament but, one of the places where we can really sink our feet into, as far as helping us to understand it is Romans 6. The reason that our union with Christ is so vital is because without it, we are not made partakers of Christ's work. It was done for us, but without us being placed in union with Christ, it remains outside of us. Our union with Christ makes His work, our work, as Romans 6 so wonderfully explains.
Our union with Christ is presented in Romans 6 as a identification for us, in that, God is identifying us, sinners saved by grace, with what Christ did. Verse 3 says our baptism into Christ Jesus was a baptism into His death. Verse 4 says we were buried with Him by baptism into death, in order that, just as Christ was raised from the the dead by the glory of the Father, we too might walk in newness of life. That is amazing!! We are resurrected now in newness of life. 2 Corinthians 5:15 provides some direction on this truth, it says: and he died for all, that those who live might no longer live for themselves but for him who for their sake died and was raised. (our newness of life is to be a life lived for him who died for us, no longer for ourselves, and why shouldn't we he rescues us from hell.)
Christ did not come to died for Himself. He came to die for us. He did not have any sin. 2 Corinthians 5:21 tells us for our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God. Galatians 3:13 tells us that Christ became a curse for us to redeem us from the curse of the law - how? by being hanged on a tree. Lest we forget, 1 Peter 2:22 says that Jesus committed no sin. So, Christ's work identified Him with us. He did them for us. Romans 6 tells us that when Christ died, we died. Verse 6 says our old self was crucified with him in order that the body of sin might be brought to nothing, so that we would no longer be enslaved to sin. This is the point we can not overlook. Our problem is sin, When Adam fell, all of humankind fell and we all sin. We need rescue from sin. God is a Holy God, Perfect in all His Being, He requires a perfect sacrifice for payment of our sins, only Christ, who committed no sin as a human could save us. He is the perfect sacrifice. The Father has so placed Christ in union with us that His perfect righteousness has been given to us, His perfect obedience has been given to us, Christ came to rescued us. The Father so identifies us with Christ that when our sins were placed on Him on the cross, the punishment for those sins, ours not Christ's, because Christ was also God, the hell we were to experience for eternity, Christ experienced for us on the cross. So, all the sins of God's people have been paid for. So when Christ is raised from the dead, so are we raised from the dead, clothed in the Perfect Righteousness of God, Himself. Romans 6 is telling us that we must also reckon or consider ourselves dead to sin and alive to God in Christ Jesus. Because it is indeed, the fact of the matter. Christ paid the penalty.
Romans 6 is answering some objections about Paul's preaching of grace, our freedom in it. He had just said in previous chapters in Romans that when sin abounded grace much more abounded. There are those who would say well if God gets glory because he gives more grace for more sin, let's sin more and gain more glory for God. Paul is saying in Romans 6 that it is not compatible with your new nature to allow sin to dominate you, in fact he says it is impossible, verse 14 says for sin will have no dominion over you, since you are not under law but under grace. The power of sin has been broken and we need to live according to what God has accomplished for us in Jesus Christ.
For those who would be so arrogant, deceived into thinking that they can play chess with God, with the kind of reasoning Paul is also addressing in this chapter he provides verse 16 for them to focus on. God will not be mocked. You will reap what you sow,
Verse 11 is a present continuous imperative in Greek, it means that it is something that we are to keep doing, we are to keep reckoning ourselves die to sin and alive to God in Christ Jesus. When you get up in the morning say "I am dead to sin and alive to God in Christ Jesus" that's not positive confession, it is faith in the commands of God. Verse 13 also tells us to present ourselves to God and our instruments to God as well (verse 19). Present yourselves to God not to sin.
Our union with Christ is to take care of sin. Sin is the destroyer, sin is what separates us from God, and each other. God sent His Holy, Perfect Son for our sake. We were the needy ones, the ones who could not rescue ourselves. We are the ones that were so enslaved to sin, that we cared not for the things of God, whether we went to hell or not. Christ came to rescue us from our blindness, our pride, our ingratitude. We have been raised in newness of life. God has placed us in union with Christ Jesus, the result of it is that we are on the way to holiness, producing no longer fruits of unrighteousness, shameful things, the end of which is death, but the fruit we strive for now are righteous and holy and they lead to the free gift of God (our union with Christ is free, we did nothing to obtain it, just like our salvation, and even our natural birth, all free gifts of God) which is eternal life in Christ Jesus our Lord. There is freedom for us as we study this great chapter in this great book of the Bible. My prayer is that God by His compassion and grace would awaken us to our privileges in Christ and encourages us to walk in them in the way He intents. In Christ name, Amen.