“Spirituality” is a broad word that covers a lot of ground. It typically begins with intellectual curiousities about the beginning of things, the purpose of existence, or other MYSTERIES OF LIFE. If it has a positive orientation, it will lead to the discovery of many wonders and the attainment of many virtues and abilities. It is a journey that has no end.
What any given individual gets out of spiritual seeking will depend totally on their orientation and focus. Because the field of spirituality is so vast it is easy for novices to quickly get lost in it, ignorantly dabbling in matters that should be left alone (like magic!).
What anyone gets out of their spiritual seeking will depend on what they desire, and what they desire will depend on their level of knowledge and maturity, and on the condition of their soul. An ignorant and immature seeker almost always gets drawn into practices that promise to give them special powers and abilities. People with some degree of knowledge (who are probably receiving direction from a shaykh/guru/shaman/etc.) will have higher aspirations for their seeking.
I have never heard of spirituality “numbing the inquisition of the critical mind.” Certain spiritual traditions advocate for and train their adherants in the TRANSCENDENCE of the critical mind, yes, because the critical mind analyzes (breaks things down) and certain Truths are so grand that they can only be grasped by an expanded consciousness.
In Islam, our orientation is positive and our focus is on Allah. What @Allahknowsbest and @johan.i.zahri said in their answers are true, but incomplete.
Knowing our purpose, where we came from, where we are going, and why we are here on Earth is entrance-level Islamic spirituality. It provides our orientation. At the deeper levels of our spiritual tradition the goal is “seek the near approach” to Allah (5:35), which means to fall deep in love with Allah and to remain in a state of constant, reverent mindfulness of Him. The result of this is a bliss, joy, and state of satisfaction that the sadnesses of mundane life cannot touch.
“And, without doubt, the remembrance of Allah is the greatest thing.” 29:45
“O you who believe! Celebrate the praises of Allah, AND DO THIS CONSTANTLY.” 33:41
“And bring your Lord to remembrance within your very soul, in humility and reverence, and without loudness in words. And do not be among those who are heedless.” 7:205
“Truly, Allah leaves to stray whom He will, but He guides to Himself those who turn to Him in penitence - those who believe, AND THOSE WHOSE HEARTS FIND REST AND SATISFACTION IN THE REMEMBRANCE OF ALLAH, for, without doubt, in the remembrance of Allah do hearts find rest and satisfaction.” 13:27-28
“And celebrate the praises of your Lord before the rising of the sun, and before its setting. Yes, celebrate them for part hours of the night and at the sides of the day, THAT YOU MAY HAVE TARDAA (pleasure and joy).” 20:130
“Those who believe are overflowing in their love for Allah” 2:165
And, no, it is not just a “good feeling” that we are pursuing. We are after “the near approach” to Allah, and that is a profound experience that no human speech can describe. The good feelings are just the fragrances of the experince, revealed to you to make you want to pursue the experience itself.
@johan.i.zahri mentioned purification. That is a major part of the process of spiritual growth.
To approach Allah the mind and heart must be cleansed of false doctrines, warped ideas, all arrogance, and other forms of profane thinking and feeling. Why do you think Allah declares the kuffaar “najis” (filthy and unclean), (9:28)? It is what their hearts and minds are full of that contaminates them.
And, though you may not like the idea of this, many muslims suffer varying degrees of contamination too. That is why He is going to complete the purification for the vast majority of us on the Day of Judgment, (4:31).
There are very few people who achieve purification while still in the Dunya, which brings me to the statement you made about an elite few. You said it as if it is part of some kind of conspiracy and scam, like there is a small group of people PRETENDING to be privy to some privileged mystical knowledge that not many are granted access to. But it‘s not like that at all, brother.
The circle is small, and has always been small - and even Allah says that about the saabiqoon (56:10-14) - but that is because there simply are not many people with the drive and determination to do the work necessary to achieve purity while still in the Dunya.
The knowledge is not a secret. All of it is right there in the Qur‘an and the Ahadith of Rasulullah (a.s.). But just KNOWING how to build a house does not get the house built. The work has to be done.
“Man can have only that which he strives for.” 53:39
Unfortunately, there are not a lot of people doing the work to attain the level of purity necessary to achieve the near approach to Allah. So the circle remains small.
In closing, let me briefly address the matter of “temporal authority” and “spiritual authority.”
Those phrases are derived from Western (i.e., European) doctrine called “the seperation of Church and State.” Once upon a time the Catholic church was the top authority over European society. Under the Church‘s leadership, steeped in superstition and ignorance, Europe fell into the dark ages. They became scientifically and politically stagnated.
After they threw off the yoke of the Church‘s leadership, they came up with the idea that people‘s relationship with “God” is a personal matter that their religious authorities can help them with. But all other aspects of society (political, economic, military, etc.) would forevermore be dealt with using only reason and the scientific method.
Under the doctrine of the seperation of Church and State, “religious authority” and “spiritual authority” are synonymous. They are the religious experts who are authorized to teach people about their relationship with “God.”
Spiritual authority, then, has nothing at all to do with spirituality, as has been explained by @Allahknowsbest, @johan.i.zahri, and myself. It‘s just a phrase invented by the kuffaar describing something that is relevant only to their way of life, not ours.
This answer is long but I pray it helps your understanding.