Is it permissible to warn people against a preacher who calls to a bid'ah (religious innovation)?

The questioner:
What is the ruling if a preacher falls into a bid'ah (religious innovation) and calls people to it? Is it permissible to warn people against him, or should one limit oneself to merely clarifying the error?

The Shaykh:
I did not understand your question.

The questioner:
If a preacher falls into a bid'ah (religious innovation) and calls people to…

The Shaykh:
If.

The questioner:
If a preacher falls into a bid'ah (religious innovation) and calls…?

The Shaykh:
To a bid'ah (religious innovation)? How can he call when he falls into innovations? Because he is ignorant; he has not learned what is a bid'ah (religious innovation) and what is the Sunnah (recommended practice). He must learn first. Well, if they argue with him, what do you say? Do you refute them except with knowledge? Do you argue with them except with knowledge? If they ask you about a matter, how do you issue a ruling for them when you are not a scholar? You say, "I do not know." He says, "Yes, so what do you call people to Allah for?" If you become someone who does not know, the one who is exposed to the da'wah (calling others to Islam) must be a learner who knows how to respond to people, how to answer their questions, and how to argue. He argues with those who do not accept, who object with doubts, and who do not fail before him, and he is the one who defeats the opponent. Yes.