This is one of the most important truths for a believer to grasp. Thomas Boston puts it like this: “The great stay of the believer is not the grace of God within him; that is a well whose streams sometimes run dry; but it is the grace of God without him, the grace that is in Jesus Christ, which is an ever-flowing fountain, to which the believer can never come amiss.”
(Thomas Boston, Human nature in its Four-Fold State, p. 312)