Final answer:
The depth of the river is symbolic of the spiritual journey and experiences of an individual, representing various aspects of human experience through allusions to significant rivers in history and metaphorical interpretations.
Step-by-step explanation:
The allegorical interpretation of Christian finding the river so deep can be linked to the richness and profundity of one's spiritual journey and experiences. This depth of soul is symbolically represented through references to historic rivers in literature and art, each river suggesting a different aspect of human experience and spiritual depth. The Euphrates associates with beginnings, the Congo with tranquility, the Nile with accomplishment, and the Mississippi with historical change and evolution. These rivers are not only geographic references but also metaphors for the stages and depths of the human experience, the trials faced, and the growth achieved, similar to the way Christians throughout history have faced persecution and sought spiritual sustenance.