Is it obligatory for a Muslim to learn the fundamentals of creed (aqidah) and monotheism (tawhid) in order to refute those who are hostile to Islam, or should they avoid them for fear of doubt?

The individual obligation (fard ayn) among the sciences is that which rectifies one's creed, worship, and profession. Anything beyond that is a communal obligation (fard kifayah). Qualifying oneself to respond to the enemies of Islam and those who cast doubts upon it is a communal obligation. If a sufficient number of people undertake it, the obligation is lifted from the rest. Anyone who ventures into this field without proper qualification causes severe and far-reaching harm. Therefore, one should not engage in it without proficiency. Whoever finds within themselves a readiness for this field must strive to acquire its tools, master its qualifications, and cooperate with specialists.