Mercy and Grace are two important theological concepts throughout the New Testament. They are listed side-by-side in 1 Timothy 1:2, and therefore refer to two separate gifts from God. Read how Lenski helpfully describes them:
ἔλεος (mercy) ". . .always deals with what we see of pain, misery and distress, these results of sin; and χαρίς (grace) always deals with sin and guilt itself. The one extends relief, the other pardon; the one cures, heals, helps, the other cleanses and reinstates." R. C. H. Lenski, The Interpretation of St. Matthew's Gospel 1-14 (Minneapolis: Augsburg Fortress, 2008), 191.
Stott on 1 John 2:24:
"Christian theology is anchored not only to certain historical events, culminating in the saving career of Jesus, but to the authoritative apostolic witness to, and interpretation of, these events. The Christian can never weigh anchor and launch out into the deep of speculative thought. Nor can he forsake the primitive teaching of the apostles for subsequent human traditions" (emphasis mine).
— John Stott, The Letters of John (Downers Grove: IVP Academic, 2009), 116.
"No one can become and remain a theologian unless he is compelled again and again to be astonished at himself. . .[he must ask] 'Who am I to be a theologian?'" — Karl Barth, Evangelical Theology: An Introduction (Grand Rapids: Eerdmans, 1992), 71.