Another possible "message" in this poem is that of death, repentance, and resurrection. There is a considerable amount of Christian symbolism in the poem as well as outright allusions to Christianity, with many passages to suggest this is a theme of the work.
The albatross seems to be a Christ symbol:
At length did cross an Albatross,
Thorough the fog it came;
As if it had been a Christian soul,
We hailed it in God's name(63-66).
In Christianity, Christ was sent by God to save mankind, as this albatross was sent to save the ship. But the Ancient Mariner kills the albatross:
'God save thee, ancient Mariner!
From the fiends, that plague thee thus!—
Why look'st thou so?'—With my cross-bow
I shot the ALBATROSS (79-82).
Subsequently, the men die as the result of being trapped on the ocean with no winds. The Ancient Mariner repents for his crime, and when he prays, the albatross, which had been hung around his neck as punishment for his sin, drops away, he falls to sleep, the winds come, and all the men return to life:
Oh sleep! it is a gentle thing,
Beloved from pole to pole!
To Mary Queen the praise be given!
She sent the gentle sleep from Heaven,
That slid into my soul (292-296).
Of course, a great deal more happens than this in the poem, and there is considerably more Christian symbolism and allusion, but even these selections are ample evidence to support a message of Christian death, repentance, and resurrection.