Is it permissible to sit with innovators in religion for the purpose of Da‘wah, especially the Sufis who have increased in number and fight the people who hold sound creed?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu 'alyhi wa sallam, is His slave and Messenger.

The basic ruling is that it is prohibited to sit with innovators in religion because it implies approval of their falsehood and it may add to their number. However, it is permissible to sit with them if it leads to a lawful interest, such as refuting their opinions or unveiling their falsehood. However, only those who have firm knowledge and the ability to refute their malicious allegations and unveil their falsehood are qualified to do this. Ibn Abbaas debated with the deviant sect of  Al-Khawaarij and Ibn Taymiyyah used to debate with innovators in religion. The common people are definitely not allowed to do this, for fear that they might be affected by the falsehood of such people. Therefore, it is clear that the ruling on sitting with or listening to such people depends on the expected outcome.

If there is no interest expected then a person should not sit with or listen to them, in accordance with the command of Allaah The Almighty in the verse (which means): {And when you see those who engage in [offensive] discourse concerning Our verses, then turn away from them until they enter into another conversion. And if Satan should cause you to forget, then do not remain after the reminder with the wrongdoing people.} [Quran 6: 68].

This is why Al-Hasan Al-Basri clarified that a person should not sit with, argue or listen to innovators in religion. [Al-Laalakaa’i].

Allaah Knows best.