what is suggested by the image of santiago stumbling up the hill toward his ome and falling to the ground under the weight of the mast

Santiago is seen a a Christ- figure. I would consider the mast as his cross. Santiago is suffering alone misjudged by those around him.

Santiago stumbling up the hill carrying the mast is indeed symbolic of Christianity. As he stumbles toward his home, he is overwhelmed by exhaustion, "he knew the depth of his tiredness" (121), and when he falls he no longer has the strength to rise.

This imagery directly correlates with that of Jesus carrying the cross. The scene culminates after three days of suffering, after which, Santiago falls into a deep sleep. Santiago's image in every way suggests the image of Christ, and might I say it's wonderfully depicted.