It is certain that in this work more than in any other by Hemmingway, religion is constantly referred to and cited. One of the definite allusions that links the story to the narrative of Christ is the way that the crucifixion is referred to. Note what Santiago says when he first spots the sharks that are ultimately going to eat his fish and take away from the glory of his accomplishments:
"Ay," he said aloud. There is no translation for this word and perhaps it is just a noise such as a man might make, involuntarily, feeling the nail go through his hands and into the wood.
Notice how Santiago is linked with the figure of Christ as he is being crucified in his moment of complete dejection and failure. Notice too, how this is echoed again as he returns to home and "shoulders the mast and started to climb," just as Jesus was made to carry his cross to Golgotha.
It appears that Hemmingway is keen to stress how Santiago in his struggle and in his defeat resembles a Christ-like figure with these allusions, that clearly gives his failure to bring the fish home to port more universal significance.