The evangelical law of charity. Love God above all things, with everything you have. And love your neighbor as yourself, for God’s sake.
At the Ecumenical Council of Trent, they discussed the relationship between faith and charity.
We believe in God. We believe in God’s Christ. We believe in the Redemption of the human race. We believe in divine love and mercy.
The Christian faith comes to us as a pure gift from above. Salvation comes as a pure gift from heaven. Our response to that gift: Belief. And grateful love.
But that doesn’t mean that we are, right now, “saved.” We have a pilgrimage to make as Christians in this fallen world, to get to the heavenly kingdom. A difficult pilgrimage. Harder than walking from London to Venice, like St. Rose of Lima’s contemporary, and William Shakespeare’s friend, Thomas Coryat did, in 1608. (In 1612, he walked from Turkey to India.) We know we cannot rely on our own strength to persevere to the end of the Christian pilgrimage. So we rely on God’s grace. We hope in God.
By hoping in God, we can live in His love. We can love with His love, and thereby fulfill the evangelical law—a task which human nature, left to itself, cannot accomplish. We neither presume on God’s mercy, nor despair of it. We persevere in faith and divine love by hoping in God’s mercy.
Faith, hope, and love. The greatest is love, to be sure. In heaven, faith and love will be no more; it will be all love. But here below: all three, inextricably intertwined. The human soul in the state of grace believes in God, hopes in God’s grace, and loves God and neighbor by God’s grace.
Father Mark White Blog 
Too right you are. God loves us just the way we are, but He loves us too much to let us stay that way (Dr. Scott Hahn). His grace is a free gift, but we are called to write daily thank you notes by cooperating with that grace by humbly and passionately obeying the summa of the commandments: Love God with your whole heart, mind, soul, and strength. And. Love. Your. Neighbor. As. Yourself.