The Baháʼí teachings represent a considerable number of theological, ethical, social, and spiritual ideas that were established in the Baháʼí Faith by Baháʼu'lláh, the founder of the religion, and clarified by its successive leaders: ʻAbdu'l-Bahá, Baháʼu'lláh's son, and Shoghi Effendi, ʻAbdu'l-Bahá's grandson. The teachings were written in various Baháʼí writings. The teachings of the Baháʼí Faith, combined with the authentic teachings of several past religions (Zoroastrianism, Hinduism, Judaism, Buddhism, Christianity, and Islam), are regarded by Baháʼís as revealed by God. The Baháʼí teachings include theological statements about God, his prophets/messengers, and humanity, as well as ethical and social teachings including the equality of all human beings regardless of gender, race, nation, colour, or social class, the harmony of science and religion, gender equality, compulsory education, and the elimination of extremes of wealth and poverty, among others. The most prominent and distinctive principles in the Baháʼí teachings are love and unity, which are exemplified by the Golden rule, and the many social principles. Shoghi Effendi, the appointed head of the religion from 1921–1957, wrote the following summary of what he considered to be the distinguishing principles of Baháʼu'lláh's teachings, which, he said, together with the laws and ordinances of the Kitáb-i-Aqdas constitute the bed-rock of the Baháʼí Faith: The independent search after truth, unfettered by superstition or tradition; the oneness of the entire human race, the pivotal principle and fundamental doctrine of the Faith; the basic unity of all religions; the condemnation of all forms of prejudice, whether religious, racial, class or national; the harmony which must exist between religion and science; the equality of men and women, the two wings on which the bird of human kind is able to soar; the introduction of compulsory education; the adoption of a universal auxiliary language; the abolition of the extremes of wealth and poverty; the institution of a world tribunal for the adjudication of disputes between nations; the exaltation of work, performed in the spirit of service, to the rank of worship; the glorification of justice as the ruling principle in human society, and of religion as a bulwark for the protection of all peoples and nations; and the establishment of a permanent and universal peace as the supreme goal of all mankind—these stand out as the essential elements [which Baháʼu'lláh proclaimed].