Source: TW
Śaṅkaradeva
Śaṅkaradeva’s Ekaśaraṇa Dharma (Assamese Vaiṣṇavism) lacked the strict caste framework, purity-pollution rules, etc. of Brahmanical Hinduism, yet it nevertheless lacked the capacity to compete with Christianity.
The sattrādhipatis were only successful at converting two groups to Vaiṣṇavism (i.e. Noctes and Wanchos of Tirap) with only a few exceptions (some Phoms, some eastern Rengma).
These two groups were unusually docile, paid nominal tribute to the Ahoms, and were vital suppliers of salt to the Ahoms along key trading routes like the Hukanjuri-Khonsa-Borduria route. Moreover, several Noctes had already adopted Theravāda Buddhism (via the Khamtis and Singphos) or Śāktism (via the Tai-Ahoms), unlike the tribes of the dangerous frontier zones.
All the schools, hospitals, nāmghars, charitable institutions, etc. established by the followers of Śaṅkaradeva (Mahāpuruṣīyas) were erected in the foothills or along the plains-hills trade corridors.
Moreover, Śaṅkaradeva’s canon (Borgeets, Kīrtanaghoṣa, etc.) was never translated from Assamese and Brôzawôli into the various Naga languages (Angami, Ao, Lotha, Sema, Chakhesang, etc.), so Vaiṣṇava converts were forced to learn and entirely new language (Assamese).
Baptists In nagaland
The Anglo-American Baptists (and, to a lesser extent Welsh Presbyterians and Catholics in the North) had the capacity and proselytizing drive that others didn’t.
In contrast, the Baptists established institutions even in remote hills, made used of the colonial state apparatus (British military columns and stockades) to outlaw headhunting raids, and translated the Bible into the various Naga languages improving literacy in their own languages.
Jews
Hindus stating “we believe all paths are true” won’t prevent Christians from proselytizing. It only disincentivizes conversion-centric activism among Hindus themselves.
Jews have a small population yet exert considerable influence. The opposite is true of Hindus. Hindus have a population exceeding 1 billion, thousands of temples, festivals, pilgrimages, etc., countless scholarly, ritual, and vernacular traditions, etc.
Other polytheists
In spite of countless divisions (by jāti, tribe, language, etc.), Hindus have an expansionary potential Druze, Bahá’í, Yazidis, Zoroastrians, Mandaeans, Yarsanists, Karaites, etc. could only dream of, yet they choose not to use it.
Hindu missions
Historically speaking, Śaivism spread across Southeast Asia, Vaiṣṇavism spread to Champa, Cambodia, and parts of Burma and Siam, and Śāktism spread to Nepal, Tibet, and Bhutan.
In spite of whatever faults they may have, organizations like RKM, ISKCON, BAPS, Chinmaya Mission, Art of Living, etc. are necessary to compete in a modern world.