I often experience during my sleep there is something unusual and pressureful at my buttock region, after which I wake up. This is very uncomfortable and sometimes circular. Is it a good sign or a bad sign? India is a place where there is a lot of tantra and cults. And people often say, "there is no such thing. This is all superstition." But these people themselves are also black magicians. How to stay protected?
The greatest protection of all is God. Pray to Him if you can, meditate, offer yourself to Him. Feel yourself in His light. Nothing can harm you if He is at your side. The Bhagavad Gita says, “My devotee is never lost.”
Another protection is high energy. If your own energy is high, you will be as if in a castle, in which negative energies, thoughts, and actions can hardly affect you.
A third protection is your own fearlessness. Fear attracts the object of that fear, like a magnet. So often affirm and practice fearlessness. Affirm with Yogananda: “Danger and I were born together, but I am more dangerous than danger.” Or with Kriyananda: “I live protected by God’s Infinite Light. So long as I remain in the heart of it, nothing and no one can harm me.”
The pressure at the buttock region you are experiencing sounds to me like a psychological phenomenon, not a spiritual one. It is uncomfortable, a pressure, meaning that it is not part of a natural joyful spiritual awakening.
I am not sure, but it might rather be related to fear, as the muladhara chakra (in the buttock region) is connected with fear of loss, of death, and of missing security.
In that case it is a good sign, simply telling you to work on yourself. It is a precious symptom which tries to stimulate you, saying “get over your fears.”
Yes, there is tantra, and various cults, some good, some less so. The awakening of kundalini they advocate is a holy thing, not a superstition. The awakening of kundalini is blissful, sacred, enlightening, and nothing of the sort of experience you are describing.
At any rate, people who doubt tantra and such are not usually black magicians. This thought too might be a fear-based thought on your part. Most people are relatively good or normal. Very few are saints, and as few are outright evil, using black magic.
May you be protected and inspired, and God bless you,