There are plenty of moral lessons throughout the word of God to point us toward moral behaviour. In fact, in the New Testament Jesus pointed us to a much higher standard than the Old. He said that adultery took place even if you lust after a woman, apart from the actual act. He said that even if we anger or hate, it is if we have committed murder. He had two reasons for these teachings. One, to show us that God's standards of righteousness are very high indeed and without Him we can do nothing good, ...and two, to point us toward a godly attitude of heart, rather than just following a set of rules.
What you've suggested is antinomianism. The belief that if Christ paid for all our sins then we can sin all the more. Paul says clearly "May it never be" and the apostolic moral teachings of the New Testament, stand alongside the moral lessons of the OT to witness to us the value of pursuing a godly lifestyle.
May God Bless