By a false display of religious sentiments, they present a show of devotional service while indulging in all sorts of immoral activities. In this way they pass as spiritual masters and devotees of God. Such violators of religious principles have no respect for the authoritative acaryas, the holy teachers in the strict disciplic succession; and to mislead the people in general they themselves become so-called acaryas, but they do not even follow the principles of the acaryas.
These rogues are the most dangerous elements in human society. Because there is no religious government, they escape punishment by the law of the state. They cannot, however, escape the law of the Supreme, who has clearly declared in the Bhagavad-gita that envious demons in the garb of religious propagandists shall be thrown into the darkest regions of hell (Bg. 16.19-20). Sri Isopanisad confirms that these pseudo religionists are heading toward the most obnoxious place in the universe after the completion of their spiritual master business, which they conduct simply for sense gratification.
(Sri Isopanisad Mantra 12)
"If the man who blasphemed Sri Caitanya Mahaprabhu is killed, his sinful action may be atoned."
The Hari-bhakti-vilasa cites the following quotation from Skanda Purana concerning the blaspheming of a Vaisnava:
                      yo hi bhagavatam lokam
                        upahasam nrpottama
                      karoti tasya nasyanti
                     nindam kurvanti ye mudha
                      vaisnavanam mahatmanam
                     patanti pitrbhih sardham
                     hanti nindati vai dvesti
                      vaisnavan nabhinandati
                     krudhyate yati no harsam
                       darsane patanani sat
In this conversation between Markandeya and Bhagiratha, it is said: "My dear King, if one derides an exalted devotee, he loses the results of his pious activities, his opulence, his reputation and his sons. Vaisnavas are all great souls. Whoever blasphemes them falls down to the hell known as Maharaurava. He is also accompanied by his forefathers. Whoever kills or blasphemes a Vaisnava and whoever is envious of a Vaisnava or angry with him, or whoever does not offer him obeisances or feel joy upon seeing a Vaisnava, certainly falls into a hellish condition."
The Hari-bhakti-vilasa (10.314) also gives the following quotation from Dvaraka-mahatmya:
                    kara-patrais ca phalyante
                     sutivrair yama-sasanaih
                     nindam kurvanti ye papa
                      vaisnavanam mahatmanam
In a conversation between Prahlada Maharaja and Bali Maharaja, it is said, "Those sinful people who blaspheme Vaisnavas, who are all great souls, are subjected very severely to the punishment offered by Yamaraja."
In the Bhakti-sandarbha (313) there is a statement concerning the blaspheming of Lord Visnu.
                      ye nindanti hrsikesam
                    tad-bhaktam punya-rupinam
                     sata-janmarjitam punyam
                      tesam nasyati niscitam
                      te pacyante maha-ghore
                       kumbhipake bhayanake
                     bhaksitah kita-sanghena
                      yavac candra-divakarau
                      sri-visnor avamananad
                 gurutaram sri-vaisnavollanghanam
                      na pasyet purusadhaman
                   taih sardham vancaka-janaih
                      saha-vasam na karayet
"One who criticizes Lord Visnu and His devotees loses all the benefits accrued in a hundred pious births. Such a person rots in the Kumbhipaka hell and is bitten by worms as long as the sun and moon exist. One should therefore not even see the face of a person who blasphemes Lord Visnu and His devotees. Never try to associate with such persons."
In his Bhakti-sandarbha (265), Jiva Gosvami further quotes from Srimad-Bhagavatam (10.74.40):
                     nindam bhagavatah srnvan
                      tat-parasya janasya va
                     tato napaiti yah so 'pi
                    yaty adhah sukrtac cyutah
"If one does not immediately leave upon hearing the Lord or the Lord's devotee blasphemed, he falls down from devotional service." Similarly, Lord Siva's wife Sati states in Srimad-Bhagavatam (4.4.17):
              karnau pidhaya nirayad yad akalpa ise
              dharmavitary asrnibhir nrbhir asyamane
           chindyat prasahya rusatim asatim prabhus cej
             jihvam asun api tato visrjet sa dharmah
"If one hears an irresponsible person blaspheme the master and controller of religion, he should block his ears and go away if unable to punish him. But if one is able to kill, then one should by force cut out the blasphemer's tongue and kill the offender, and after that he should give up his own life."

(C.C. Madya Lila 15.261)