Proofs of the existence of God have been discussed, written down and disseminated from the time of the ancient Greek philosophers, Hebrew prophets and Indian holy men. Books and articles about such proofs are published every year, in many languages. Among the authors of such proofs in modern times are Mirza Husayn 'Ali Nuri, called Bahá'u'lláh (1817-1892) and his son 'Abbas, called 'Abdu'l-Bahá (1844-1921). Both were born in Tehran, Iran and deceased in the Holy Land. Peter Terry has collected, compiled and correlated the proofs he found in English translations of writings and talks by Bahá'u'lláh and 'Abdu'l-Bahá, and presents them in this volume with minimal commentary and hopefully maximal clarity. This volume does not pretend to provide an exhaustive study of such proofs, as this would require access to, study and translation of many texts available only in Arabic and Persian, which is beyond the scope of this modest work. Perhaps others will be inspired by the perusal of this slender compilation to undertake a more comprehensive study of the subject.