Perhaps the most difficult task for us to perform is to rely on God's grace

"Perhaps the most difficult task for us to perform is to rely on God's grace and God's grace alone for our salvation. It is difficult for our pride to rest on grace. Grace is for other people - for beggars. We don't want to live by a heavenly welfare system. We want to earn our own way and atone for our own sins. We like to think that we will go to heaven because we deserve to be there."

RC Sproul

In the Presence of God: Devotional Readings on the Attributes of God 2003