Intellectual setting
Rāmānuja worked within the South Indian Śrīvaiṣṇava devotional and temple tradition centered at Srirangam, drawing on the Tamil bhakti poetry of the Āḻvārs as well as Sanskrit Vedantic exegesis, and directly engaged and rejected the dominant Advaita Vedānta of Śaṅkara's followers; tradition holds that doctrinal conflict forced him into a period of exile in Karnataka.
Key ideas
Viśiṣṭādvaita, qualified non-dualism
Against Advaita's claim that Brahman is without qualities (nirguṇa) and that plurality is ultimately illusory (māyā), Rāmānuja argued Brahman is qualified (saguṇa) by real attributes and that souls and matter are real, eternally distinct yet inseparable modes of Brahman, related to it as body to soul (śarīra-śarīri-bhāva).
Bhakti and self-surrender as the path to liberation
Rāmānuja's Śrī Bhāṣya and Gītā Bhāṣya developed a theology of loving devotion (bhakti) and self-surrender (prapatti) to a personal God, Viṣṇu-Nārāyaṇa, as the central means of liberation (mokṣa), integrating devotional practice with systematic Vedantic exegesis of the Upanishads, Brahma Sūtras, and Bhagavad Gītā.
Legacy
Rāmānuja's Viśiṣṭādvaita became the doctrinal foundation of Śrīvaiṣṇavism, one of the major devotional traditions of Hindu India, and his synthesis of rigorous philosophical exegesis with bhakti theology influenced later Vedantic schools, including Madhva's Dvaita Vedānta, and remains central to ongoing scholarly and sectarian debate over the interpretation of the Brahma Sūtras and Upanishads.