Apologetics is the branch of theology which seeks to defend a religion's tenets through reasoned argument. Bahá'ís generally believe that the proof of the truth of the religion can be found through independent investigation. In Bahá'í thought, the validity of the various Manifestations of God, prophets in the Bahá'í writings that include Jesus, Muhammad, Gautama Buddha and Bahá'u'lláh among others, is reasoned through the power of the word of God, the revelation of divine verses, the characteristics of the prophets, the fulfillment of prophecy, and the teachings brought by the prophet; miracles, however, are not regarded as proof of divinity.
Many apologetic books have been written in response to attacks on the religion's history and teachings. The religion's founders themselves wrote several books in response to such questioning presenting proofs of their religion, among them are the Báb's Seven Proofs and Bahá'u'lláh's Kitáb-i-Íqán. Later Bahá'í authors wrote prominent apologetic texts, such as Mírzá Abu'l-Fadl's The Brilliant Proof and Udo Schaefer et al.'s Making the Crooked Straight; and today there is an extensive library of such resources.
Schaefer's book was written to refute a polemic supported by the German Protestant Church. Scholarly reviews styled Schaefer’s book as “an important contribution to the critical study of the Bahá’í religion” “clarifying many misconceptions” and presenting “a picture of the Baha’i Faith that no future researcher in the field can afford to overlook”. Since its publication the German Protestant Church has revised its own relationship to the German Bahá’í Community and came back to dialogue.
This page attempts to provide a broad overview of some of the issues in question that may be considered challenging in nature. This page has been divided into sub-categories that go into more detail.
Central teachings 
- Bahá'ís believe in the fundamental agreement in purpose of all the major world religions. At the same time it is incontrovertible that there are many differences between the different religions. Naturally, a large amount of apologetic literature has been published on how these diverse points-of-view are reconciled in the Bahá'í teachings.
- Bahá'ís assert that gender equality is an incontrovertible reality of the human condition. Certain teachings seem to favor one gender or the other in education, inheritance, and membership on the Universal House of Justice.
- Bahá'ís believe that science without religion leads to materialism, and religion without science leads to superstition. The idea that these two seemingly opposite forces are in harmony is fundamental to Bahá'í teachings. This particular question is however not without problems.
- Bahá'ís call for a universal auxiliary language, meaning in addition to one's native tongue.
Issues discussed elsewhere 
- Diverse issues in many countries including Bahá'í persecution and a focus on teachings and action over numbers, makes statistics complex to understand.
- Bahá'í teachings only permit sexual relationships between a married husband and wife.
- The Bahá'í Faith has had several challenges to leadership.
- The Bahá'í Faith identifies itself as the fulfillment of the Bábí Faith. The separation of the two, beginning in 1863, was accompanied by conflict and murders.
- Bahá'ís have been accused of being agents or spies of Russia, Britain, the Shah, the United States, and of Zionism—each claim being linked to each regime's relevant enemy and justifying anti-Bahá'í actions. The last claim is partially rooted in the presence of the Bahá'í World Centre in northern Israel. The Shah of Iran and the Caliphate were responsible for the decision to banish Bahá'u'lláh to the prison city of 'Akká (in what was then Palestine) in the first place.
- Although polygamy is forbidden by Baha'i law, Bahá'u'lláh had three concurrent wives.
- Bahá'ís wishing to publish books about the Bahá'í faith must first submit their work to their respective National Spiritual Assembly for approval through a review process. This process has not been without its critics.
- Smith, Peter (2000). "apologetics". A concise encyclopedia of the Bahá'í Faith. Oxford: Oneworld Publications. pp. 39–40. ISBN 1-85168-184-1.
- Bahá'í Studies Review, Volume 8, 1998
- More precisely: by the Evangelische Zentrale für Weltanschauungsfragen (EZW); cp. A paper about the EZW by Silja Joneleit-Oesch (University of Heidelberg, Germany) for the Center for Studies on New Religions
- Manfred Hutter (Dep. of Religious Studies, Graz) in Journal of Contemporary Religion, Vol. 12, 1997, pp. 437-439
- Heshmat Moayyad in Journal of the Royal Asiatic Society, Vol. 8, 1998, pp. 451-454
- Ulrich Dehn in Materialdienst der Evangelischen Zentralstelle für Weltanschauungsfragen (EZW), 1/1997, pp. 14-17: “Baha’i und EZW”
- Momen, Moojan (2007). "Marginality and Apostasy in the Baha'i Community". Religion 37: pp. 187–209. Retrieved 5–3–2012.
- Abrahamian, E. (1993). Khomeinism: Essays on the Islamic Republic. Berkeley, CA: University of California Press. ISBN 978-0-520-08503-9.
- Affolter, Friedrich W. (2005). "The Specter of Ideological Genocide: The Bahá'ís of Iran". War Crimes, Genocide and Crimes Against Humanity 1 (1): 59– 89.
- Buck, Christopher (2003). "Islam and Minorities: The Case of the Bahá'ís". Studies in Contemporary Islam 5 (1): 83–106.
- Effendi, Shoghi (1974). Bahá'í Administration. Wilmette, Illinois, USA: Bahá'í Publishing Trust. ISBN 0-87743-166-3.
- Schaefer, U.; Towfigh, N.; Gollmer, U. (2000). Making the Crooked Straight: A Contribution to Bahá'í Apologetics. Oxford, UK: George Ronald. ISBN 0-85398-443-3. OL 11609763M.
- The Bahá'í Faith as Panopticon, by Juan Cole, detailing his criticisms of the American Bahá'í community.