Paul rejects the attitude of those who would consider themselves justified before God on the basis of their own works. Such people, even when they obey the commandments and do good works, are centered on themselves; they fail to realize that goodness comes from God. Those who live this way, who want to be the source of their own righteousness, find that the latter is soon depleted and that they are unable even to keep the law. They become closed in on themselves and isolated from the Lord and from others; their lives become futile and their works barren, like a tree far from water.
--Pope Francis, Lumen Fidei