Most people practice rituals without understanding anything about them. It is largely a habit and tradition reinforced further by the need for conformity, social approval, fears and favours. Quite naturally they cannot explain. Your questioning reminds them of this inadequacy and instead of trying to know, understand and become conscious (the right response to questions whose answers we may not know) they become aggressive and ignorantly defensive (common response). It is no use disturbing them. Let them follow what they think is best. As for yourself you can politely but firmly express your reservations and tell them that you have your own path to the Divine and want to be left free to follow it. At most you can explain to them that you have your reasons to follow what you feel is best just as they have theirs. If they insist then practice equanimity.
Family is often the best ground for practicing a benevolent samata since one cannot escape away or avoid them. Benevolent because one may act indifferently with a kind of superior condescending attitude. but benevolence is full of a luminous understanding of the natural limitations of human beings and even when we do not and must not follow their way (each must find his own) yet there need not be any quarrel over it. Even it is possible to find a common meeting ground such as a Godward seeking or bhakti (though directed towards different Deities) and leave it at that. I know it is not easy but take it as a degree exams, this one in equanimity.
