Hunger, sickness and war are examples of crisis.

Birth and death are crises.

Marriage is usually regarded by humanity as a crisis.

So is initiation--the turning-point in one's career, when one steps out into the world of men.

Now what, in terms of mind, does crisis mean?
It means that one is at one's wits' end; that the ordinary and expected has been replaced by the extraordinary and unexpected; that we are projected into the world of the unknown.
And in that world of the unknown we must miserably abide until, somehow, confidence is restored.
Psychologically regarded, then, the function of religion is to restore men's confidence when it is shaken by crisis.