However, Christians are not under the law, but under grace...
"Under the Law" means what? It means under the condemnation of the Law. So I look at the Law and see "No stealing". I look at my neighbors tool shed unlocked and open and think I could get me some tools. According to God, that is the same as stealing. The only way to please God is to follow His Law and keep His Commandments and let God guide our thoughts. He must write His Laws in our heart. We have to do our part.
God could have saved Noah without him building an ark but man must always do our part. James 2:26 For as the body without the spirit is dead, so faith without works is dead also.