Adi 7.48-–On the basis of scriptures like Śrīmad-Bhāgavatam, which reveal these confidential directions, Śrī Caitanya Mahāprabhu instructed Sanātana Gosvāmī regarding all the regular activities of a devotee.
PURPORT-In the paramparā system, the instructions taken from the bona fide spiritual master must also be based on revealed Vedic scriptures. One who is in the line of disciplic succession cannot manufacture his own way of behavior. There are many so-called followers of the Vaiṣṇava cult in the line of Caitanya Mahāprabhu who do not scrupulously follow the conclusions of the śāstras, and therefore they are considered to be apa-sampradāya, which means “outside of the sampradāya.” Some of these groups are known as āula, bāula, kartābhajā, neḍā, daraveśa, sāṅi sahajiyā, sakhībhekī, smārta, jata-gosāñi, ativāḍī, cūḍādhārī and gaurāṅga-nāgarī. In order to follow strictly the disciplic succession of Lord Caitanya Mahāprabhu, one should not associate with these apasampradāya communities.
One who is not taught by a bona fide spiritual master cannot understand the Vedic literature. To emphasize this point, Lord Kṛṣṇa, while instructing Arjuna, clearly said that it was because Arjuna was His devotee and confidential friend that he could understand the mystery of the Bhagavad-gītā. It is to be concluded, therefore, that one who wants to understand the mystery of revealed scriptures must approach a bona fide spiritual master, hear from him very submissively and render service to him. Then the import of the scriptures will be revealed. It is stated in the Vedas (Śvetāśvatara Upaniṣad 6.23):yasya deve parā bhaktir yathā deve tathā gurau
tasyaite kathitā hy arthāḥ prakāśante mahātmanaḥ
“The real import of the scriptures is revealed to one who has unflinching faith in both the Supreme Personality of Godhead and the spiritual master.” Śrīla Narottama dāsa Ṭhākura advises, sādhu-śāstra-guru-vākya, hṛdaye kariyā aikya. The meaning of this instruction is that one must consider the instructions of the sādhu, the revealed scriptures and the spiritual master in order to understand the real purpose of spiritual life. Neither a sādhu (saintly person or Vaiṣṇava) nor a bona fide spiritual master says anything that is beyond the scope of the sanction of the revealed scriptures. Thus, the statements of the revealed scriptures correspond to those of the bona fide spiritual master and saintly persons. One must therefore act with reference to these three important sources of understanding. https://prabhupadabooks.com/cc/adi/7/48
 
Some Conclusions--From the above we collect this important information. To understand the param para sampradaya one must be like Arjuna-a devotee and confidential friend of the Lord. If one acts properly, following strictly the bona fide guru, then he or she will understand the sastra. However if one acts in a way that is improper like offending  Vaisnavas, then it is simply not possible to understand Krsna, nor how His energies are working. 
So when one offends others, commits sins, speculates, or a host of other offenses to the Holy Names, does this mean at that point in time this “devotee” is in or out of the param para?  If one is outside the param para does that mean he has become a sahijiya? Let us consider the following.

Oct 6 1967 letter….
Kirtanananda may be eager to address in the Harvard university but recently he has lost his link on account of disobedience. You sing every day morning that by the mercy of the Spiritual master one can please the Lord and one who has not pleased the spiritual master cannot have any access in the realm of Krishna Consciousness. Very recently Kirtanananda has developed a different consciousness of Maya which is called misuse of one’s minute independence offered by Krishna. By misuse of one’s independence one at once becomes a victim of Maya and thus he loses all importance in Krishna Consciousness. So it is my definite opinion that his lecture anywhere now will bear no spiritual sequence. He must rectify his mistake before he can play in our Society any important role. By lips he says that he is a surrendered soul but by action he is thinking differently.
Therefore Srile Prabhupada says ….”The real import of the scriptures is revealed to one who has unflinching faith in both the Supreme Personality of Godhead and the spiritual master.”
If one is committing sinful acts like above mentioned, it is not possible to understand what one is reading right in front of him, or even if his actions are sinful. As Prabhupada says above
…”There are many so-called followers of the Vaiṣṇava cult in the line of Caitanya Mahāprabhu who do not scrupulously follow the conclusions of the śāstras,”….
Also we can gather from the Naradiya Purana as stated by Lord Vishnu that there are 10 kinds of devotional service. All but one is contaminated by the modes of nature.      If one is contaminated– how is it possible to act 100% purely?
Or if one is offending or has offended another devotee then how is that that person  is going to get the blessings of action and knowledge of guru and God while sinning?
When Kirtanananda was doing his “thing” he was thinking ‘this is all spiritual activity and Prabhupada will approve my actions.’ Boy was he ever wrong !
If one maintains a humble attitude then is is almost impossible to offend others, what to speak of other Vaisnavas. But if one does that, then what happens to that person?
Here again is what the sastra says…
Madhya 15.261
PURPORT/….In this conversation between Mārkaṇḍeya and Bhagīratha, 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. Vaiṣṇavas are all great souls. Whoever blasphemes them falls down to the hell known as Mahāraurava. He is also accompanied by his forefathers. Whoever kills or blasphemes a Vaiṣṇava and whoever is envious of a Vaiṣṇava or angry with him, or whoever does not offer him obeisances or feel joy upon seeing a Vaiṣṇava, certainly falls into a hellish condition.”
 
The Hari-bhakti-vilāsa (10.314) also gives the following quotation from Dvārakā-māhātmya:
 Prahlāda Mahārāja and Bali Mahārāja, it is said, “Those sinful people who blaspheme Vaiṣṇavas, who are all great souls, are subjected very severely to the punishment offered by Yamarāja.”
So how do we know if we have insulted or offended a Vaisnava? Either he will say so or a friend of his may do so, but it will be made known. And the best evidence is that if one offends others, if he or she is a genuine Vasnava, then that devotee should himself feel very badly for his actions within his own heart. And then make  amends with that offended Vaisnava.
Then the whole issue will be over.
The very first offense to chanting the Holy names of God-to blaspheme or unnecessarily criticize the devotees of the Lord who have dedicated their lives to Krsna.
Hare Krsna
damaghosa das