In his sermon What think ye of Christ? George Whitefield helpfully says
Every man that is saved is justified three ways: First, Meritoriously, by the death of Jesus Christ: "It is the blood of Jesus Christ alone that cleanses us from all siu." Secondly, Instrumentally, by faith: faith is the means or instrument whereby the merits of Jesus Christ are applied to the sinner's heart: "Ye are all the children of God by faith in Christ Jesus." Thirdly, We are justified Declaratively, namely, by good works: good works declare and prove to the world, that our faith is a true saving faith. "Was not Abraham justified by works?" And again, "Shew me thy faith by thy works."