20 And now, my beloved brethren, seeing that our merciful God has given us so great knowledge concerning these things, let us remember him, and lay aside our sins, and not hang down our heads, for we are not cast off;
24 Wherefore, my beloved brethren, reconcile yourselves to the will of God, and not to the will of the devil and the flesh; and remember, after ye are reconciled unto God, that it is only in and through the grace of God that ye are saved.
Jacob’s weaving of the strands of his father’s teaching culminates in this masterful invocation to action. Again, Jacob weaves the three themes of agency, the gathering of Israel, and the power of the atonement with truly moving rhetoric.
Jacob gives the people several reasons to rejoice. First of all, because of what he has taught regarding the gathering of Israel, Jacob can assure them that they are not cast off. Second, Jacob rejoices in the great knowledge that his people has of god’s plan thanks to the revelations of his father and brother. Thus, Jacob can lay forth the Gospel plan with far greater clarity, and unfold things that were not manifest to those in Jerusalem. Next, his people should “cheer up [their] hearts” because they have been made free to act thanks to Christ’s atonement. Finally, they can have access to the grace of God and overcome “the will of the devil and the flesh.”
I love how Jacob (and Nephi) turn Isaiah’s message of the destruction that hangs over Israel into a declaration of faith, hope, and joy. They saw that God’s plan was not concerned with short term outcomes, but with eternal patterns and occurrences. Thus, despite the scattering and the exile of the people of Israel, Jacob could take great comfort from the promise of their return.