First, after the fall of Isengard, Aragorn looks into the palantir of Orthanc to face Sauron. Why? Well, it's revealed that, as the heir of Isildur, Aragorn is the rightful owner of the palantiri. And as the rightful owner, Aragorn acts to wrest control of the seeing stone away from Sauron.
Second, seeing in the palantir a threat to Gondor coming from the south, Aragorn elects to take the Paths of the Dead. By taking this route to Gondor, Aragorn seeks to reverse the curse Isildur placed upon the Men of Dunland, who broke their vow to support Isildur in the War of the Last Alliance against Sauron. Isildur's curse caused the Men of Dunland to linger upon the earth as restless shades. In taking the Paths of the Dead, Aragorn will reverse the curse of Isildur by enlisting the shades of the Men of Dunland in the coming battle of Gondor.
And beyond these two actions, there's the general plot line that Aragorn's entire life has been devoted to undoing the damage Isildur unleashed upon Middle Earth in failing to destroy the Ring of Power when he cut it off Sauron's hand.
In all of this we see in Aragorn the coming of a Second Isildur, which is why the last book of the trilogy is called "The Return of the King." And as the New Isildur we see Aragorn repairing the damage of the Old Isildur. The palantir is regained. The curse on the Men of Dunland is lifted. The Ring of Power will finally be destroyed.
We don't think about him much in this way, but Adam was a king, given dominion and rule over the earth. But that primordial king damaged the world. Good things, like the palantir, became corrupted. Curses were placed over sinners. Evil was unleashed into the world.
But in Christ a new King has come, a Second Adam. And through this Adam, the damage that was done by the first is healed and mended. In theology, this is called the recapitulation theory of the atonement, how the Second Adam undoes the damage of the First Adam, the new king repairing the damage of the old. This was a hugely influential theology of salvation among the early church fathers, but one we don't hear much about today as we have focused on penal and forensic visions of atonement.
But the atonement theology of The Lord of the Rings is recapitulation. We don't see any of the principal characters die in a way that might image the crucifixion of Jesus. What we do see is the return of the king, salvation coming in the New Isildur who repairs and mends the damage of the old.
