The unregenerate man cares nothing about the will of God. He is at enmity with God. He cares only for himself. Everything he does, regardless of how outwardly noble, is done for his own self-interest.
Then how do unregenerate people do things from the heart that are God's will like what Christ said the Samaritan did? There is no law against such things, which means it's not sin, which is what God wills.