The Law was only a shadow of good things to come. That means we can now sin all we want. On the contrary. For the grace of God has appeared, bringing salvation to all men, instructing us to deny ungodliness and worldly desires and to live sensibly, righteously, and godly in the present age. Grace is actually a higher law than the Old Testament Law.
Airplanes can fly because the law of aerodynamics is a higher law than the law of gravity.
Grace changes our hearts so that we want to do God's will. We are now under the law of the Spirit who lives within every believer, and are not under the letter of the Law. For the letter kills, but the Spirit gives life.