It is a synthesis of various traditions, the "Brahmanical orthopraxy, the renouncer traditions and popular or local traditions". Theism is also difficult to use as a unifying doctrine for Hinduism, because while some Hindu philosophies postulate a theistic ontology of creation, other Hindus are or have been atheists. Despite the differences, there is also a sense of unity. Most Hindu traditions revere a body of religious or sacred literature, the Vedas, although there are exceptions. These texts are a reminder of the ancient cultural heritage and point of pride for Hindus, with Louis Renou stating that "even in the most orthodox domains, the reverence to the Vedas has come to be a simple raising of the hat". Halbfass states that, although Shaivism and Vaishnavism may be regarded as "self-contained religious constellations", there is a degree of interaction and reference between the "theoreticians and literary representatives" of each tradition that indicates the presence of "a wider sense of identity, a sense of coherence in a shared context and of inclusion in a common framework and horizon". The notion of common denominators for several religions and traditions of India further developed from 12th century CE. Lorenzen traces the emergence of a "family resemblance", and what he calls as "beginnings of medieval and modern Hinduism" taking shape, at c. 300 – 600 CE, with the development of the early Puranas, and continuities with the earlier Vedic religion. Lorenzen states that the establishment of a Hindu self-identity took place "through a process of mutual self-definition with a contrasting Muslim Other". According to Lorenzen, this "presence of the Other" is necessary to recognise the "loose family resemblance" among the various traditions and schools. According to the Indologist Alexis Sanderson, before Islam arrived in India, the "Sanskrit sources differentiated Vaidika, Vaiṣṇava, Śaiva, Śākta, Saura, Buddhist, and Jaina traditions, but they had no name that denotes the first five of these as a collective entity over and against Buddhism and Jainism." This absence of a formal name, states Sanderson, does not mean that the corresponding concept of Hinduism did not exist. By late 1st-millennium CE, the concept of a belief and tradition distinct from Buddhism and Jainism had emerged. This complex tradition accepted in its identity almost all of what is currently Hinduism, except certain antinomian tantric movements.