The knowledge of Christ's love for us should cause us to love Him in such a way that it is demonstrated in our attitude, conduct, and commitment to serve God. Spiritual maturity is marked by spiritual knowledge being put into action.
The law demands good works and uses its terror--rejection, shame, fear of punishment, unanswered prayer, personal tragedy, etc.--as motivation. Here performance is a necessity to secure the blessings and avoid the curses. Grace, on the other hand, allows us to serve on a different basis--not from fear but on the basis of love and gratitude, from appreciation and gladness for blessings freely given and freely received.