No religion appeared out of nowhere. Judaism gave birth to Christianity, and both form the backdrop of Islam's self-understanding; the Vedic tradition and the śramaṇa movement grew into Hinduism, Jainism and Buddhism; Buddhism, moving east, interpenetrated Daoism, Confucianism and Shinto. This map gathers the links scattered across each issue's "cross-tradition bridge" into one network — solid lines are descent, dashed lines are influence, double-headed lines are mutual absorption.
WhoJesus — a Jewish teacher in Roman-ruled Palestine; after his death, disciples like Peter kept meeting; and Paul — a Pharisee who had persecuted the group, then converted and became its greatest missionary.
WhatAround 30 CE Jesus was executed by the Roman governor. By the expectations of the age, the Messiah (the "anointed one," God's promised deliverer) was supposed to restore Israel — execution meant failure. But the disciples proclaimed that Jesus had risen, and that he was the Messiah. At first the message spread only among Jews; Paul insisted that gentiles (non-Jews) could join directly, without circumcision or the Jewish law. The Council of Jerusalem (c. 49) sided with him — and the door opened to the whole Roman world.
OutcomeBelievers were increasingly gentiles, drifting away from the synagogue; after Rome destroyed the Jerusalem Temple (70) and crushed the great Jewish revolt of 132–135, the two communities parted for good — an internal Jewish movement had grown into an independent religion.
WhoThe Prophet Muhammad's followers. The dispute centered on two men: Abu Bakr (one of the Prophet's earliest companions) and Ali (his cousin and son-in-law).
WhatMuhammad died in 632 without an undisputed succession plan. Who should be caliph — the successor who leads the community? The majority acclaimed Abu Bakr; others held the Prophet had already designated Ali. Ali did become the fourth caliph, only to be assassinated amid civil war; in 680 his son Husayn was killed by Umayyad troops at Karbala (in today's Iraq) — a massacre that made the breach irreparable.
OutcomeThe majority came to be called Sunni ("followers of the Prophet's practice"), Ali's partisans Shia ("the party of Ali"). What began as a succession quarrel grew over centuries into two different systems of religious authority (Shia Islam has a line of Imams; Sunni Islam does not). Today Sunnis are ~85–90% and Shia ~10–15%, concentrated in Iran and Iraq; Karbala remains the memory Shia Muslims mourn every year.
WhoIn the West, the Pope in Rome and his legate Cardinal Humbert; in the East, Patriarch Michael I of Constantinople. Behind them: the Latin-speaking church of Western Europe versus the Greek-speaking church of the Eastern Roman (Byzantine) Empire.
WhatGrievances had piled up for centuries. The West had added a phrase to the shared creed — the Holy Spirit proceeds "and from the Son" (Latin: filioque) — which the East saw as tampering with the common faith. The deeper issue was authority: Rome held that the Pope headed the whole church; the East would grant him only "first among equals." In 1054 negotiations collapsed: the papal legate slammed a bull of excommunication (a decree of expulsion from the church) onto the altar of Hagia Sophia, and the Patriarch excommunicated the legate right back.
OutcomeContemporaries took it for one more quarrel; in hindsight it was a permanent parting. In 1204 the Fourth Crusade — a Western army — sacked Constantinople, the Eastern capital, sealing the hatred. The West became Catholicism, the East Orthodoxy; the excommunications were symbolically lifted in 1965, but communion has never been restored.
WhoMartin Luther — a monk and theology professor at Wittenberg in Germany; then Zwingli in Zurich, Calvin in Geneva, and others.
WhatThe spark was indulgences — certificates sold by the church promising reduced punishment after death. In 1517 Luther published his Ninety-five Theses in protest: the power to forgive sin belongs to God, not the church. He went further — sola scriptura (scripture, not pope or tradition, is the final standard of faith) and justification by faith (God accepts people through faith, not accumulated good works). The church expelled him, but the newly spread printing press carried his pamphlets across Europe, and princes took sides out of conviction or politics.
OutcomeThe churches that broke with Rome became "Protestant," and kept branching — Lutheran, Reformed/Calvinist, Anglican and more. After a century of religious wars, the Peace of Augsburg (1555) settled on "whose realm, his religion," and the Peace of Westphalia (1648) ended the fighting — largely fixing Europe's confessional map to this day.
WhoSiyyid Ali-Muhammad — a young merchant of Shiraz, Iran, who took the title "the Báb" (Arabic for "the Gate"); and his follower Bahá'u'lláh.
WhatShia Islam awaits the Twelfth Imam — hidden, not dead, and destined to return. In 1844 the Báb announced that he was the gate to this hidden one, and then that he brought a new revelation of his own — apostasy, by mainstream law. The movement spread fast, was bloodily suppressed, and the Báb was publicly executed in 1850. He had foretold another still to come, "He whom God shall make manifest"; in 1863 the exiled Bahá'u'lláh declared that he was that one.
OutcomeBahá'u'lláh's teaching — one human family, one source behind all religions, revelation unfolding age by age (Moses, the Buddha, Jesus, Muhammad and himself as messengers of a single process) — grew into the Baha'i Faith: an independent world religion, not an Islamic sect. It is scattered worldwide, and still persecuted as apostasy in its birthplace, Iran.
WhoBands of ascetics in the Ganges basin who left home to seek liberation ("śramaṇa" means "one who strives"); the two most consequential: Mahavira (revered by Jains as their great teacher) and Siddhartha Gautama, the Buddha.
WhatThe establishment religion was the Vedic tradition: Brahmin priests monopolized sacrifice and taught that ritual, done correctly, secures blessings. Urbanization and warring kingdoms loosened the old order, and some began to ask: does sacrifice actually work? How does one truly escape the cycle of rebirth? They abandoned household and caste identity to seek answers in austerity and meditation — an open challenge to Brahmin authority.
OutcomeTwo living religions grew from the ferment: Jainism (the path of radical nonviolence and asceticism) and Buddhism (the middle way). The shock also forced the Vedic tradition to renew itself from within — the Upanishads turned sacrifice inward, and karma, rebirth and liberation became the shared substrate of all Indian religion; the Hinduism to come took shape in that very conversation.
WhoCentral Asian merchants and monks carried Buddhism in along the Silk Road; generations of translator-monks relayed it onward — An Shigao (Eastern Han), Kumārajīva (brought to Chang'an in 401 to head a translation bureau), Xuanzang (who traveled to India for nearly twenty years in the 7th century).
WhatBuddhism arrived around the Eastern Han, the 1st century (legend has Emperor Ming dream of a golden man and found the White Horse Temple, 68 CE). At first the Chinese grasped it through Daoist vocabulary; over centuries it argued with Daoism and Confucianism (does leaving home violate filial piety? must monks bow to the emperor?) while absorbing from both — producing schools that had never existed before, such as Chan (Zen) and Pure Land. The Huichang persecution of 845 was the heaviest blow — but by then Buddhism was rooted too deep in popular life to destroy.
OutcomeBuddhism became thoroughly Chinese and traveled on to Korea, Japan and Vietnam, forming the East Asian Mahayana world. From the Song dynasty on the saying ran, "Confucianism governs the world, Daoism the body, Buddhism the mind" — in folk practice the three merged: the same person could honor ancestors (Confucian), consult diviners (Daoist) and chant to the Buddha, with no felt contradiction. That blend is the "three teachings" folk ecology.
WhoThe fusion was the joint work of the Japanese court, shrines and temples over centuries; the separation was one decree of the new Meiji government in 1868.
WhatAfter Buddhism reached Japan in the 6th century, the native kami (spirits) were not displaced but cross-interpreted. The popular theory, honji suijaku, held that Japan's kami were local manifestations of buddhas and bodhisattvas, appearing in Japanese form to save the Japanese. So shrines chanted sutras and temples enshrined kami — one fabric for nearly a thousand years. In 1868 the Meiji government, rebuilding national identity around the emperor, decreed the separation of kami and buddhas: shrines and temples were forcibly split, and Shinto was elevated into a state ideology (State Shinto). A wave of temple-smashing (haibutsu kishaku) followed, destroying temples and images across the country.
OutcomeInstitutionally, Shinto and Buddhism have been separate ever since (State Shinto was dissolved after Japan's defeat in 1945). But popular habit never split: many Japanese visit a shrine at New Year and hold funerals at a Buddhist temple — both tracks, no contradiction felt.
WhoSome 12.5 million West Africans shipped to the Americas by the slave trade — above all Yoruba, Fon and Kongo peoples.
WhatIn the colonies the enslaved were forcibly baptized Catholic and their ancestral religion was banned. But the Yoruba orisha — spirits governing nature and human affairs — mapped uncannily well onto the Catholic saints: behind Saint Barbara's image one could venerate Shango, spirit of thunder; saints' feast days became days of offering to the orisha. Under prohibition, the faith survived inside a Catholic shell.
OutcomeThe fusion grew into different religions in different colonies: Vodou in Haiti, Candomblé in Brazil, Santería in Cuba. They are not the "witchcraft" of lurid stories but complete religious systems — alive today and officially recognized (Brazil's constitution protects Candomblé's religious standing).
This map presents the historical connections between traditions from a neutral, comparative standpoint, drawing only links widely recognized by scholarship; "descent" arrows indicate direction of historical development and imply no ranking. Points of dispute (the degree of Zoroastrian influence, the framing of Sikh independence, etc.) are noted in the text.