There was a demon of the name Vrkasura. He was the son of Sakuni. Vrkasura went to Kedarnatha, which is a pilgrimage in Kashmir in order to ignite a sacrificial fire to please Lord Siva. He has heard from Narada Muni that from the three deities: Vishnu, Brahma, Siva, it is Siva who can fulfill the benediction of his devotee fastest. After igniting the fire, Vrkasura began to offer his own flesh into the fire. This is the example of worship in the mode of ignorance as stated in the Bhagavad-gita: "Penance performed out of foolishness, with self-torture or to destroy or injure others, is said to be in the mode of ignorance." (Bg 17.19)
Persons who perform such so-called sacrifice are declared by Krsna to be demons. He says: "Those who undergo severe austerities and penances not recommended in the scriptures, performing them out of pride and egoism, who are impelled by lust and attachment, who are foolish and who torture the material elements of the body as well as the Supersoul dwelling within, are to be known as demons." (Bg 17.5-6) So it was very clear from the sastric point of view that this Vrkasura was a first class demon. The worship of Lord Visnu or Krsna is very simple, and it can be executed by anyone in this world since a devotee can please the Lord very easily by offering a simple fruit, leaf, water or flower. But worship in the mode of ignorance, as exhibited by Vrkasura, is not only very difficult and painful but is also a useless waste of time. Therefore the Bhagavad-gita says that the worshipers of the demigods are bereft of intelligence. Vrkasura continued such horrible sacrifices for 6 days but he was unable to physically meet Lord Siva in order to get the benediction. This is the difference between a devotee and a demon.
Srila Prabhupada comments in this connection: "A devotee is confident that whatever he offers to the Deity in full devotional service is accepted by the Lord, but a demon wants to see his worshipable deity face to face so that he can directly take the benediction. A devotee does not worship Visnu or Lord Krsna for any benediction. Therefore a devotee is called akama, free of desire, and a nondevotee is called sarva-kama, or desirous of everything. (KB 88: The Deliverance of Lord Siva) A devotee is satisfied with the vibrational presence of his worshipful Deity since his only objective is to serve, but those who are full of material desires want to physically see the Lord in order to engage the Lord in their service. The very insistance for the Lord to be present is a sign of trying to command the Lord instead of serving Him. For this reason such less intelligent worshippers rarely approach Lord Visnu or his bona fide representative for spiritual guidance. Instead they take shelter of demigods or physically present pseudo Gods who are always ready to serve their foolish followers with temporary and useless boons from the realm of sensualism. Vrkasura, being unable to physically associate with Lord SIva then started contemplating cutting off his own head and offering it to the sacrificial fire. He was so lusty to satisfy his material desires. At this point, Lord Siva, the epitome of compassion came to save the demon. The demon then asked a benediction from Lord Siva, which was most dangerous and foolish. Vrkasura asked Lord Siva for a special ability to crack one's head upon touching it. Lord Siva very unwillingly gave such benediction, but instead of being grateful to his benefactor, the foolish demon started chasing Lord Siva in order to test the benediction on Lord Siva first. These are the dealings of demons.
There is a class of offensive persons who similarly attempt to subject the acharya to the rulings of the sastra. Their undertaking is non-different from the offensive mentality of Vrkasura in connection with Lord Siva. Instead of being eternally indebted to the acharya for teaching them the sastra, as soon as they learn a little, they want to attack the acharya and take his place. No genuine Vaishnava can be fooled by the pretentious display of devotion performed by such over-intelligent persons. He never takes part in their so-called worship of the acharya but avoids them as a plague since he is fully aware of the effects of bad association. They take shelter of the statements of the Caitanya-caritamrta, which clearly declare:
dharma-sthapana-hetu sadhura vyavahara
"A devotee's behavior establishes the true purpose of religious principles.
(Madhya 17.185)
tarko ‘pratisthah srutayo vibhinna
nasav rsir yasya matam na bhinnam
dharmasya tattvam nihitam guhayam
mahajano yena gatah sa panthah
Dry arguments are inconclusive. A great personality whose opinion does not differ from others is not considered a great sage. Simply by studying the Vedas, which are variegated, one cannot come to the right path by which religious principles are understood. The solid truth of religious principles is hidden in the heart of an unadulterated, self-realized person. Consequently, as the sastras confirm, one should accept whatever progressive path the mahajanas advocate.'"
(Madhya 17.186)
Srila Prabhupada confirms about various acharya's vibrational presence to be non-different from the sastra:
"The statements of Thakura Bhaktivinode are as good as scriptures because he is liberated person."
(Letter to: Janardana -- New York 26 April, 1968)
"Anything sung in the praise of the Lord is Sruti-mantra. There are songs of Thakura Narottama dasa, one of the acaryas in the Gaudiya-sampradaya, composed in simple Bengali language. But Thakura Visvanatha Cakravarti, another very learned acarya of the same sampradaya, has approved the songs by Thakura Narottama dasa to be as good as Vedic mantras. And this is so because of the subject matter. The language is immaterial, but the subject matter is important."
(SB 1.10.20)
The very Vedic sastras both sruti and smrti are written by a liberated spiritual master Srila Vyasadeva. No intelligent person will hear a person who does not represent the original acharya.