A primary distinction can be made between locally rooted urban cults (e.g., in the Greek city-states, in Jerusalem, and in Rome) and religious sects (e.g., Orphism, Mithraism, Manichaeism, and Christianity) based on voluntary affiliation through initiation. The cults of the city were centered around animal sacrifices, festivals, and (with the exception of Judaism) polytheistic cult of imagery, while sectarian religiosity had a clearer orientation towards personal salvation and hinside faith. A third, more loosely defined form of religiosity with no direct connection to the previous two categories includes such things as magic, alchemy, divination, incubations, and various forms of unofficial folk piety.
The religions or antiquity – many of which gradually died out in connection with the spread of Christianity and Islam and its elevation to urban religions in late antiquity and the early Middle Ages – have since the 1800s been the subject of intensive study through a rich variety of texts (in the form of epigraphic material, papyrus fragments and medieval transcripts of ancient texts), iconography, temple architecture, tombs, etc.
The study of the characteristics and interrelationships of the religions of antiquity is of central importance for the understanding of the early history and development of the three so-called Abrahamic religions. Judaism, Christianity and Islam still bear a strong imprint of the religious beliefs, ethical systems and rituals of the ancient Mediterranean cultures.