The archetype of a journey across water is sometimes used in literature to represent a hero's purification. what effect does christian's crossing of the river have in pilgrim's progress? it implies that in order to reach salvation, one needs to have a , like hopeful. it warns readers that getting to the celestial city is nearly impossible. it shows that if christian can cross into the celestial city, ordinary people can, too. it demonstrates that christian, despite his prior sins, has finally earned salvation.

I believe the correct answer is: It implies that in order to reach salvation, one need to have a helper, like Hopeful.

     The archetype of a journey across water, which represents hero's purification, has the same effect of purification for Christian's crossing of the river  in “Pilgrim's Progress” (1678), a Christian allegory written by John Bunyan, but in religious context:

     “Christian doubts whether he can make it across, for the memory of his past sins weights on him one again, but Hopeful reminds him that Christ’s love would take away those sins.”

     This allegory implies that in order to reach salvation, one need to have Hope. The Hope is one of three pillars of Christianity, alongside Love and Faith. In the final part, it’s implied that only true hope and belief can preserve one on his journey to Heaven, but the Vain Hope cannot:

     “Ignorance has crossed the river on a ferry called Vain Hope, and yet he will not be admitted to the Celestial City, because he doesn’t have a scroll-ticket.”