Romans 6:1-2, 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?
Paul continues to say Baptism is what kills us in sin and makes us alive in Christ (vv. 3-23). Unbelievers are without excuse for their unbelief (1:20). In the same way, baptised Christians are without excuse for unrepentance. Baptism does not grant licentiousness—the licence to sin without remorse and confession, otherwise Christ died for nothing. If you believe you’re forgiven and think that means Christ allows you to live in sin, then you misunderstand the Gospel.
Forgiveness does not give us freedom to sin, but freedom from sin. As Paul puts it, sin no longer has dominion—power, authority—over the baptised Christian (6:14). Also, as Paul says soon thereafter, “So now, it is no longer I who do it, but sin that dwells within me” (7:17), “for the law of the Spirit of life has set you free in Christ Jesus from the law of sin and death” (8:2). Sin remains in us, yet because of Christ, God no longer considers us as willing participants, since sin no longer has authority over us.