Grace

"What shall we say then? Are we to continue in sin that grace may abound? By no means! How can we who died to sin still live in it?" - Romans 6:1-2 "For you were called to freedom, brothers. Only do not use your freedom as an opportunity for the flesh, but through love, serve one another." - Galatians 5:13
These verses say it all. Some Christians may think, "I am free from the wages of sin; Christ paid my debt on the cross. I can sin all I want now, because I am a Cristian and God is gracious, therefore He will forgive me." May it not be so! If you are a follower of Jesus Christ, then do just that: follow Jesus Christ. Don't use grace as an opportunity to sin. Jesus called us to a life of freedom, hope, love, and faith. Not just a life of sin. We must set an example to the rest of the world, not fall back into their ways.
Romans 6:15 "What then? Are we to sin because we are not under law but under grace? By no means! Do you  not know that if you present yourselves to anyone as obedient slaves, you are slaves of the one whom you obey: either of sin, which leads to death, or of obedience, which leads to righteousness?