What is the dominant force in the life of a believer who is under grace instead of law?

Love is the dominant force in the life of a believer under grace rather than law. Because love fulfills the Law, when love operates, the believer does not commit adultery, kill, bear false witness, or covet, and fulfills the command to love neighbor as self.

Les teaches that grace does not mean a believer may do as he pleases or sin as he pleases; that is not grace. Romans asks whether we should sin because we are not under Law but under Grace, and the answer is God forbid. Although believers are not under Law with its penalties, God's mind on sin has not changed; the things called abominable in Leviticus remain abominable to God. Since we are under Grace, love is the dominant force now in the believer's life. Love is the fulfilling of the Law, so when love is operating, the believer does not commit adultery, kill, bear false witness, or covet, and the other commandments are summed up in loving your neighbor as yourself. Paul repeats nine of the Ten Commandments, omitting the Sabbath.

Romans 13:8

Owe no man any thing, but to love one another: for he that loveth another hath fulfilled the law.

How is the law fulfilled under grace according to Romans 13?

Under grace, loving another person fulfills the law. Once believers step under grace and the Holy Spirit empowers them, love becomes the motivating power behind everything they do, so they automatically fulfill the Law. This replaces temple worship, priesthood, animal sacrifices, and constant drilling of the Ten Commandments.