If then you have been raised with Christ, seek the things that are above, where Christ is, seated at the right hand of God. Set your minds on things that are above, not on things that are on earth. For you have died, and your life is hid with Christ in God. When Christ who is our life appears, then you also will appear with him in glory.
Put to death therefore what is earthly in you: fornication, impurity, passion, evil desire, and covetousness, which is idolatry. On account of these the wrath of God is coming. In these you once walked, when you lived in them. But now put them all away: anger, wrath, malice, slander, and foul talk from your mouth. Do not lie to one another, seeing that you have put off the old nature with its practices and have put on the new nature, which is being renewed in knowledge after the image of its creator. Here there cannot be Greek and Jew, circumcised and uncircumcised, barbarian, Scythian, slave, free man, but Christ is all, and in all. Colossians 3:1–11 (RSV)
If you are baptized, you have been raised with Christ. We have been baptized into the death and resurrection of Jesus. Our old nature has been put to death, and we now live in Christ. God acts in the waters of baptism, and we are a new creation.
This simple explanation of who is a Christian is the starting point for our new life in Christ. We see the things of this life, of this world, in the light of Christ. We recognize so many things that would stand between our Lord and us. We see that, though we are redeemed in Christ, sin is all around us, striving to draw us away from the Lord.
St. Paul lists some of the ways in which sin shows itself in our lives. It is not an exhaustive list. If you don't find your pet sin in this passage of Scripture, it does not mean that you are off the hook. A Christian is never wholly free of sin on this side of Jesus' return. We are, to be honest about that, sinners.
We are forgiven sinners whose deepest desire is to become more like Jesus every day. A Christian lives life with eyes wide open. We see our sin clearly, making no excuses for it. We name it for what it is, bring it to the foot of the Cross, seeking the new life our Lord grants through His mercy.