The first We knew of Him was Death — Abraham Lincoln

The first We knew of Him was Death－¹
The second－was－Renown－
Except the first had justified
The second had not been.

(F.1006/J.1006)

[1] Him: Abraham Lincoln, and Jesus Christ.
[2] second: second life, the Resurrection; fame is one's second life, hinted by renown. Renown: of the Resurrection.
[3, 4] first had justified, second, not: His death had justified, but His second life, Resurrection, had not. The death of Abraham  Lincoln is known, and his fame is to be justified in the future.