Mercy Or Grace??

What is the difference between Mercy & Grace? There's a big shift in usage between the OT and the Gospels and the Pauline Epistles. Can God use Satan to show His Mercy and Grace? Let's examine Job and Paul experiences. Mercy and Grace are lot closer than you think. When was the first time "Grace" was mentioned in the Bible? When was the last time? Is "grace" possible without "faith"? Did you know there is no word in English to define "Mercy"?