Answer: Shaykh Muhammad ibn Saalih al-'Uthaymeen رحمه الله replied,
"When a person has knowledge and insight into that which he is calling to, then there is no difference between the one who has a great amount of knowledge, or a student of knowledge who has recently started in pursuit of knowledge or a lay person as long as he has certain knowledge of the issue at hand.
The Prophet صلى الله عليه وسلم said: 'Convey from me, even if it is one verse.' [1]
So it is not a condition upon the daa'ee (the one calling) to attain a great amount of knowledge, but the condition is that one must have knowledge of what one is calling to. If this calling is established upon ignorance and built upon emotion and passion, then it is not permissible.
Thus, we see that some of the brothers who call to Allaah سبحانه و تعالى, they do not have except a little knowledge. We see them, due to their strong emotions, prohibiting that which Allaah سبحانه و تعالى has not prohibited, whilst making obligatory that which Allaah سبحانه و تعالى has not made obligatory upon His worshippers. This is a very dangerous matter, since permitting what Allaah سبحانه و تعالى has made Haraam (unlawful) is like prohibiting what Allaah سبحانه و تعالى has made Halaal (lawful). So when they begin prohibiting people for making a particular matter then others will rebuke them for making it Haraam.
Allaah تعالى says:
'And do not say, concerning that which your tongues falsely put forward, "This is lawful and this is forbidden," so as to invent lies against Allaah. Indeed, those who invent lies against Allaah will never prosper.' [Surah al-Nahl (16):116-117]
As for the lay person, then he must not call to Allaah سبحانه و تعالى if he does not have knowledge. Rather, it is essential to have knowledge in accordance with the saying of Allaah سبحانه و تعالى:
'Say: (O Muhammad صلى الله عليه وسلم): "This is my way; I invite unto Allaah (i.e. to the Oneness of Allaah - Islamic Monotheism) with sure knowledge, I and whosoever follows me (also must invite others to Allaah i.e to the Oneness of Allaah - Islamic Monotheism) with sure knowledge. And Glorified and Exalted be Allaah (above all that they associate as partners with Him). And I am not of the Mushrikeen (polytheists, pagans, idolaters and disbelievers in the Oneness of Allaah; those who worship others along with Allaah or set up rivals or partners to Allaah)."' [Surah Yoosuf (12):108]
So it is a must to call to Allaah سبحانه و تعالى upon knowledge. However, if a matter is clearly known to be evil or good, then one can command it if it is good, or forbid it if it is evil.
So the callers to Allaah سبحانه و تعالى must start with knowledge. Whosoever calls to Allaah سبحانه و تعالى without knowledge, then such a person will cause greater harm than good as is evident. So it is obligatory for a person to first acquire knowledge, then to do Da`wah. As for the clear evils and that which is clearly good, then the good is enjoined and the evil prohibited." [2]
Notes:
[1] Saheeh al-Bukhaaree.
[2] Shaykh Muhammad ibn Salih al-'Uthaymin رحمه الله, The Islamic Awakening (Al-Hidaayah Publishing, UK), pp. 105-106.