A spiritual threat is one that forces us to reassess our beliefs. Most often it will contain options of action that lead to a degree of inevitability either way. Once on that particular path we have no choice but to continue.
In dreams the image of a divided path or road will often occur at this time, or of going up or down. You might also like to consult the entry for path as well as the information on archetypes, anxiety dreams and nightmares in the introduction.