ye ca tān samanuvratāḥ
pāṣaṇḍinas te bhavantu
One who takes a vow to satisfy Lord Śiva or who follows such principles will certainly become an atheist and be diverted from transcendental scriptural injunctions.
It is sometimes seen that devotees of Lord Śiva imitate the characteristics of Lord Śiva. For example, Lord Śiva drank an ocean of poison, so some of the followers of Lord Śiva imitate him and try to take intoxicants like gāñjā (marijuana). Here the curse is that if someone follows such principles he must become an infidel and turn against the principles of Vedic regulation. It is said that such devotees of Lord Śiva will be sac-chāstra-paripanthinaḥ, which means “opposed to the conclusion of śāstra, or scripture.” This is confirmed in the Padma Purāṇa also. Lord Śiva was ordered by the Supreme Personality of Godhead to preach the impersonal, or Māyāvāda, philosophy for a particular purpose, just as Lord Buddha preached the philosophy of voidness for particular purposes mentioned in the śāstras.
Sometimes it is necessary to preach a philosophical doctrine which is against the Vedic conclusion. In the Śiva Purāṇa it is stated that Lord Śiva said to Pārvatī that in the Kali-yuga, in the body of a brāhmaṇa, he would preach the Māyāvāda philosophy. Thus it is generally found that the worshipers of Lord Śiva are Māyāvādī followers. Lord Śiva himself says, māyāvādam asac-chāstram. Asat-śāstra, as explained here, means the doctrine of Māyāvāda impersonalism, or becoming one with the Supreme. Bhṛgu Muni cursed that persons who worshiped Lord Śiva would become followers of this Māyāvāda asat-śāstra, which attempts to establish that the Supreme Personality of Godhead is impersonal. Besides that, among the worshipers of Lord Śiva there is a section who live a devilish life. Śrīmad-Bhāgavatam and Nārada-pañcarātra are authorized scriptures that are considered sat-śāstra, or scriptures which lead one to the path of God realization. Asat-śāstras are just the opposite.