No matter where we look for the cause of our spiritual crises, it is basically always a crisis of faith. One can have many problems in life, but as long as one maintains faith, he still moves forward; when he begins to stagnate, it is not because he is lacking something from the outside, that is, he should be provided with better conditions, but because he is losing faith inside.
What is faith? It is certainly a belief in something, but it would not be enough to say that, because any fanaticism or denial of reality is a belief too. Faith, as it follows from Scripture, is the adherence of the heart to God.