When we enter a spiritual system, we are usually given a whole bunch of things to believe and do. But if you want to wake up, then cultivating great doubt (the willingness to examine and deeply question everything) is of the utmost importance.
This willingness to examine and question everything rapidly exposes the unquestioned set of assumptions we have been living our life out of. This is a frightening and disturbing experience as the world, others and ourselves are not as we think they are. We rapidly realize we have been quite delusional. The world as we have known it falls apart.
It is at this time that the dark night of the soul, the desert experience, existential depression, nihilism, fatalism, angst and atheism may arise because, having lost what we have thought is so, we have nothing to replace it with. Our philosophical mind will tell us it is all pointless as life is empty and meaningless. We may as well go jump off the bridge.
This half-bakked state of despair is precisely where one needs a good teacher. Most of those without a teacher often end up cynical, hopeless and depressed. For awakening to occur it must be fully realized that the conceptual, intellectual, philosophical mind cannot think its way to liberation.
Another dimension of being must be called forth. This is Great Faith. Faith in this moment just as it is. This is where sitting quietly, doing nothing adds fire to the red hot iron ball of doubt cooking deep within our bellies. Resting as effortless, choiceless, silent awareness.
And then suddenly something stops happening. The problem you are stops. In all directions there is only vast freedom, freedom from what you once imagined yourself to be and freedom to be what you always already are, freedom to allow life to be as it is. Something wonderful and inexpressible has happened.
The greater the doubt, the greater the enlightenment.