Grace is is an act. To return Good for Evil is the very essence of Christ's work on the Cross. Grace is also a state of being. If I live in grace then grace must flow from my life into the lives of others. If nothing flows, there is no presence of God in my Life.
"...above all, taking the shield of faith with which you will be able to quench all the fiery darts of the wicked one." Eph 6:16