The third element was the worship of the sky god. This was the fundamental creed of the ancient Turks, and in this particular form appears only among them. In this system of belief, the sky god (Tangri, Tengri) is the Supreme Being, the central object of all worship, the source of all power. The Old Turks followed a religious tradition that blended shamanism with what Western scholars have named “Tengrism,” a faith worshiping Heaven (Türk. Tengri) as the supreme God and venerating certain mountains as seats of power. Tengrism was never an organized religion and appeared in several forms among almost all the peoples of the Central Asian steppes – Türk, Mongol, and Tangut alike. In its Turkic form, it supported the Turkic social structure, which was built on the basis of a hierarchy of tribes. One tribe is dominant and its chief is the source of a hereditary line of rulers for all. The Turkic form of Tengrism, then, regards any Turkic chief controlling Otukan as supreme ruler (Türk. qaghan) of all Turkic tribes and embodiment of society’s fortune. If Turkic society’s fortune declined, the Khagan was accountable and could even be sacrificed. His son would then succeed to his position.
The principle beliefs and practices of the Tangri cult can be more or less determined by a study of Chinese sources and the Orkhon monuments. In a letter sent to the Chinese emperor by Mo-tun, the ruler of the Asian Huns, the latter notes that he had been elevated to the throne by Tangri and that his military victories were won first and foremost by virtue of the sky god's grace. Another Hun ruler, having escaped a trap set for him by the Chinese in 133 B.C. declared that his deliverance had been the will of Tangri, who watched over him and ensured his success. A Turkish ruler in 328 is reported as raising his arms to the heavens upon having achieved a success and saying "O Sky (Kok)… Thanks be to thee!" In the treaty between the Avar the Khagan and the Byzantine emperor, the former swore to uphold the agreement in the name of Kok-Tangri. After a victorious battle in 598 or 599, the Blue Türk (KokTürk) the Khagan Tardu dismounted, addressed the sky and proclaimed his thanks. According to the inscriptions on the Orkhon monuments, Tangri was the creator of the universe. The Blue Turks believed that their empire's formation was a consequence of the sky god's wishes and that their khagan had been sent to them by their god. In other words, Tangri took a personal interest in the independent existence of the Turks. Victory in the battle was a consequence of Tangri's will. Tangri intervened directly in the lives of the Turks and of people in general. He commanded and punished the disobedient. Tangri bestowed fortune and retracted it from those who were unworthy. It was Tangri who broke the light of day at dawn and who fused vegetation with life. Death was also dependent upon his will. Tangri granted life and could take it back whenever he wished: "When his time came, Kul Tegin died. Human beings are created to die. Law and right come from Tangri. He joins that which is broken and mends that which is torn."
The progress of the development of the concept of Tangri among the Turks from that of the physical sense of "sky" to a supreme being is interesting. In the Orkhon inscriptions there is a sentence that sums up the Turkish cosmogony in a nutshell: "Uze kok Tengri, asra yagiz yer kilindikta ikin ara kisi ogli kilinis" (When almighty Kok-tangri formed the dark yonder-earth, he also created man). To these early steppe landers the vast over-arching sky seemed to embrace everything from the phenomenal rising and setting of the sun and moon to the regular movements of the stars; from the unchanging cycle of the seasons to rain, snow, and wind; the heat of the day and the cold of the night; the quickening of vegetation in spring and its desiccation in summer; the sudden flowing of streams and their dying up; the birth and growth of animals in an invariable order and balance whose harmony was so perfect that it was inconceivable to the mind of man, and it was only natural that they should have regarded it as a supreme being. In addition to the absolute might of Tangri's immortality, Tangri also acquired the attribute of being everywhere at all times and of being incapable of being represented physically.
It has also been asserted that totemism was practiced among the early Turks; however, recent investigations have disproved this allegation. Researchers working in Siberia and Mongolia during the second half of the 19th century put forth an assertion that the early Turks were originally shamanists. Although incorrect, this notion became widespread and still persists.
In the course of their long history and wanderings, Turkish groups came into contact with many other religions prior to Islam. Some groups in China adopted Buddhism. The Danube Bulgars opted for Christianity. Judaism was popular with the Khazars. The Uighurs adopted Buddhism and Manichaeanism. The consequences for Turkish identity were not always providential since these groups were eventually assimilated into the larger communities.
Buddhism earlier than all great religions became popular in the first Turk khaganate aristocratic environment. The third son of Bumen (Il-Qağan) and Wei Chang'le, and the fourth khagan of the Gokturk khaganate Taspar reigned from 572-581. Unlike his father and older brothers he embraced chinese culture, especially Buddhism. He was converted to this religion by the Qi monk Huilin, for whom he built a pagoda. It is known from the Bugut inscription (VI c.) at court of Taspar khagan lived Sogdians-Buddhists. The Bugut inscription itself was written with the script typical for Buddhist sutrs. The khaganate rulers saw in Buddhism a universal form, that could help to creating a certain ideological community in the heterogeneous power. However, a social-political crisis in the khaganate begun in 581 г. Halted this process. In the west and east of the khaganate Buddhism was kept for some time. Some spreading Buddhism got among the Yenisei Kyrghyz and the Kimaks. One of the princes of the Yenisei Kyrghyz princely house even became a Buddhist monk, settled in one of the Buddhist monastery of Eastern Turkestan and translated sacred texts from Tibetan into Turkic.
A bronze mirror with a runic inscription found in a burial place of a Kimak woman in Eastern Kazakhstan, was decorated with a Buddhist maxim in the Turkic language. However only the Uighurs of Eastern Turkestan adopted Buddhism as a state religion and created the richest heritage of Buddhist texts translations, written in India, Tibet, Eastern Turkestan. Another religion spread among the Turks was Manichaeism. Manichaeism (Manichaeanism), dualistic religious movement founded in Persia in the 3rd century ad by Mani, who was known as the “Apostle of Light” and supreme “Illuminator.” Although Manichaeism was long considered a Christian heresy, it was a religion in its own right that, because of the coherence of its doctrines and the rigidness of its structure and institutions, preserved throughout its history a unity and unique character. Mani was born in southern Babylonia (now in Iraq). With his “annunciation” at the age of 24, he obeyed a heavenly order to manifest himself publicly and to proclaim his doctrines; thus began the new religion. From that point on, Mani preached throughout the Persian Empire. At first unhindered, he later was opposed by the king, condemned, and imprisoned. After 26 days of trials, which his followers called the “Passion of the Illuminator” or Mani’s “crucifixion,” Mani delivered a final message to his disciples and died (sometime between 274 and 277). Mani viewed himself as the final successor in a long line of prophets, beginning with Adam and including Buddha, Zoroaster, and Jesus. He viewed earlier revelations of the true religion as being limited in effectiveness because they were local, taught in one language to one people. Moreover, later adherents lost sight of the original truth. Mani regarded himself as the carrier of a universal message destined to replace all other religions. Hoping to avoid corruption and to ensure doctrinal unity, he recorded his teachings in writing and gave those writings canonical status during his lifetime.
The Manichaean Church from the beginning was dedicated to vigorous missionary activity in an attempt to convert the world. Mani encouraged the translation of his writings into other languages and organized an extensive mission program. Manichaeism rapidly spread west into the Roman Empire. From Egypt it moved across northern Africa (where the young Augustine temporarily became a convert) and reached Rome in the early 4th century. The 4th century marked the height of Manichaean expansion in the West, with churches established in southern Gaul and Spain. Vigorously attacked by both the Christian Church and the Roman state, it disappeared almost entirely from Western Europe by the end of the 5th century, and, during the course of the 6th century, from the eastern portion of the Empire. During the lifetime of Mani, Manichaeism spread to the eastern provinces of the Persian Sāsānian Empire. Within Persia itself, the Manichaean community maintained itself in spite of severe persecutions,