Why we should not associate with bad sects in islam ?

Question -  should we associate with people who call themselves Muslims but who have the wrong belief and
practice that belief -  whabbism deobandis tabligh jamat etc ?

Answer -   I will try to provide you with the answer from ahle sunnat jamat books and hadith books

The Holy Prophet (sallal laahu alaihi wasallam) clearly warned his Ummah to completely abstain from joining in the
gatherings of or listening to the words of any of the other misguided groups that will appear amongst the Muslims,
whose beliefs will contradict the beliefs of the largest group of Muslims.

The Holy Prophet (sallal laahu alaihi wasallam) said: "In the period prior to the Day of Judgement, false and
deceitful groups will emerge. They will say things to you, which neither you nor your forefathers will have ever heard
before. Stay away from these deceitful people and do not let them come near you! Do not be misguided by them
and do not let them cause strife amongst you!" (Sahih Muslim)

Ghousal Azam, Hazrat Sheikh Abdul Qadir Jilani (radi allahu anhu) states: "There are 73 groups as foretold by
Sayyiduna Rasoolallah (sallal laahu alaihi wasallam) and (bear in mind that), the Ahle Sunnat wal Jamaat was the
rightful group". (Ghunyatut Taalibeen)

Imam Rabbani, Mujaddid Alif Thaani (radi allahu anhu) states in the second chapter, page 67 of his "Maktubaat
Shareef" that: "The way of salvation is followance of the Ahle Sunnat Wal Jamaat. May Almighty Allah Ta'ala bestow
blessings upon the Ahle Sunnat Wal Jamaat, in their speech, in their actions, laws, for this is the successful group.
Besides this, all other groups have become victims of deception. Today, nobody realises how much these misled
groups will be punished, however, on the Day of Qiyamah this secret will become apparent. Even though at that
time this knowledge will be of no benefit to the misled."
Imam Sadiq (as) said: "Be careful of your knowledge and see from whom you get it."
The Holy Prophet (saaw) said: "Man is influenced by the faith of his friends. Therefore, be careful of whom you
associate with."

A person with eyes protruding, with a long beard and head clean-shaven came to the Prophet (Sallalaahu Alayhi
Wasallam) and declared: ‘O Muhammad (Sallalaahu Alayhi Wasallam) fear Allah.’" The Prophet (Sallalaahu Alayhi
Wasallam) replied: "If I disobey Allah then, who else will obey Him? I am obedient to Allah at all times and never
disobedient. Allah has sent me as Amin (Honest) for the entire world, but you don’t accept me as an honest man?"
A Sahabi (Companion) became infuriated and sought permission to remove him from the presence of the Prophet
(Sallalaahu Alayhi Wasallam). The Prophet (Sallalaahu Alayhi Wasallam) prevented the Sahabi from doing so. After
the person had left, the Holy Prophet (Sallalaahu Alayhi Wasallam) said: "From his progeny will rise a Group who
would recite the Holy Quran but it will not go below their throats. They will leave the Deen just as an arrow leaves
the bow-string. They will kill the Muslims but spare the idolators. If I ever confronted these people I would slaughter
them just as the people of Aad had been destroyed." (Mishkat Shareef pp/535)

You may eat some rotten food and your stomach might become upset and you will induce vomiting but whoever
listens to something no good cannot get rid of it so easily, and it may stay with him until the end of his life. It is for
this reason that our Grandshaykh cautioned his murids against listening to scholars who deny tariqats and
murshids, for maybe they will poison you. If a person sits with such deniers, he must be prepared to carry a heavy
burden of darkness and live with an injured heart for one year.(Shaykh Nazim Mercy Oceans Hidden Treasure
book).

My Grandshaykh was explaining what the Prophet means by this hadith: oh sons of adam, you must take good
people for friends; if you keep company with bad people, they might harm you physically or otherwise, in our times
we must be very careful of this. Our Grandshaykh explained that people are susceptible to both good and bad
characteristics. The Holy Prophet said: a man is of the same religion as his friend. Everyone has an innate capacity
for both good and evil. If someone is going with a good man, then his good characteristics will appear, but if he is
going with bandits, he will also become a bandit. .(Shaykh Nazim Mercy Oceans Hidden Treasure book).