Romans 6:8-11 “Now if we have died with Christ, we believe that we will also live with him. We know that Christ, being raised from the dead, will never die again; death no longer has dominion over him. For the death he died he died to sin, once for all, but the life he lives he lives to God. So you also must consider yourselves dead to sin and alive to God in Christ Jesus.“
Christians have died to sin and are united with Christ when we put our faith in Him even if we don’t realize it. The believer’s union with Christ is essential because He represents us before God, and everything good about Christ is applied to us. Our death to sin means it has no more reign over us, though we will still see sin in our lives.
At the same time, we are alive to God, and grace reigns in our lives as we pursue holiness. This is all from grace, and in our union with Christ we find the identity and the strength to do what is impossible apart from the grace of God — namely, to be holy.