Any messenger, any incarnation, saktyavesa-avatara, teaches according to the time and circumstance: desa, kala, patra. That they do not consider. Therefore other groups beyond the Vedic group, they come forward to compete with the Vedic group without knowing their own position. That is their defect. Always remember this: the teacher is M.A., but the students are not competent to take instruction of him. Therefore you find different types of religion.
From Srila Prabhupada’s lecture, 27 Dec 1970, Surat