The Covenant of Grace is defined in the WCF : "Man by his fall having made himself incapable of life by that covenant, the Lord was pleased to make a second, commonly called the covenant of grace: wherein he freely offered unto sinners life and salvation by Jesus Christ, requiring of them faith in him, that they may be saved, and promising to give unto all those that are ordained unto life, his Holy Spirit, to make them willing and able to believe." Chap. 7:3. Preaching the gospel entails a setting forth and an expounding of the terms of this Covenant. Saving faith is a believing and receiving the mercy offered freely under the terms of the Covenant. This Covenant is most secure and certain since it is undergirded by the oath of God. "To perform the mercy promised to our fathers, and to remember his holy covenant; The oath which he sware to our father Abraham," Luke 1:72-73.