Contemporary Hinduism can be categorized into four major traditions: Vaishnavism, Shaivism, Shaktism, and Smartism. Vaishnavism, Shaivism, and Shaktism worship Vishnu, Shiva, and Devi — the Divine Mother — as the Supreme respectively, or consider all Hindu deities as aspects of the formless Supreme Reality or Brahman. Other minor sects such as Ganapatya and Saura focus on Ganesha and Surya as the Supreme. A sub-tradition within the Vaishnavism school of Hinduism that is an exception is dualistic Dvaita, founded by Madhvacharya in the 13th-century (where Vishnu as Krishna is a monotheistic God). This tradition posits a concept of monotheistic God so similar to Christianity that Christian missionaries in colonial India suggested that Madhvacharya was likely influenced by early Christians who migrated to India, a theory that has been discredited by scholars.