Interesting scripture pairing. The first is Jacob's writing.
Jacob 4:12 And now, beloved, marvel not that I tell you these things; for why not speak of the atonement of Christ, and attain to a perfect knowledge of him, as to attain to the knowledge of a resurrection and the world to come?
2 Nephi 11:2 And now I, Nephi, write more of the words of Isaiah, for my soul delighteth in his words. For I will liken his words unto my people, and I will send them forth unto all my children, for he verily saw my Redeemer, even as I have seen him.
3 And my brother, Jacob, also has seen him as I have seen him; ....
The second scriptures makes clear that there is nothing academic in the meaning of the first scripture. When Jacob said "why not come to a perfect knowledge of Christ and a knowledge of the resurrection and the world to come", he was speaking as man who had begun to come to a perfect knowledge of the Christ, the same as his brother Nephi had.
And he asks us why we should not do the same.