Romans 6:10-14
For in that he died, he died unto sin once: but in that he liveth, he liveth unto God. Likewise reckon ye also yourselves to be dead indeed unto sin, but alive unto God through Jesus Christ our Lord. Let not sin therefore reign in your mortal body, that ye should obey it in the lusts thereof. Neither yield ye your members as instruments of unrighteousness unto sin: but yield yourselves unto God, as those that are alive from the dead, and your members as instruments of righteousness unto God. For sin shall not have dominion over you: for ye are not under the law, but under grace.
Once we have been baptized and our sin has been left behind. It is important for us to not to go back to the way we were. Sin will not have any more control over us if we follow and trust Jesus. Many people think that they have to clean themselves up before coming to Christ, but this is thinking of the Devil. Christ will take us any way we are. He will make us clean and help us stay that way.