We are made dead to sin, meaning our relationship to sin is dead. But sin is not dead to us. We still have sin in our members.
Rom 7:5 - For when we were in the flesh, the motions of sins, which were by the law, did work in our members to bring forth fruit unto death
The law brings sins into motions.
Rom 7:7 -What shall we say then? Is the law sin? God forbid. Nay, I had not known sin, but by the law:for I had not known lust, except the law had said, Thou shalt not covet
Rom 7:8 -But sin, taking occasion by the commandment, wrought in me all manner of concupiscence. For without the law sin was dead
Rom 7:9 -For I was alive without the law once:but when the commandment came, sin revived, and I died
Without the law, sin in our members is dead, but the moment we try to use the law to live a pleasing life to God, sin in our members is revived and our functional christian life(the way we should live) is dead and we are allowing sin to reign in our lives. God does not want us to live our lives under a law, because we will constantly see that sin in our members and sin is not dead to us. But sin shall not have dominion over us, for we are dead to sin and alive unto God and we should reckon ourselves to be dead indeed unto sin.