At personal level, i agree that very act of religious conversion is stupid. Rationality and Science ,while unable to disprove existence of god, have proven that a control freak vengeful God is an impossibility.
Genuine Religious conversion (99.999% are not.They are by Sword,Money,or for marriage) is symptom of grave identity crisis that a person has suffered at time of his conversion. It is pretty different from becoming Atheist or Agonist where you move out of the concept of religion.
But having said that, it is important not to overlook that religions does not have spiritual function alone. They have very strong Socio-cultural function. It is due to this function that i would prefer that most of Indian become or remain nominal or cultural Hindus.And there are important real life precedence in contemporary world to prove that i am right.
Religions, especially those who proselytize aggressively, are vehicles of ethnic imperialism.
Take Islam; It is a blatant vehicle of Arab imperialism. Every muslim has to pray facing mecca, has to undertake pilgrimage to Arabia, and in Islam Syeds ie Arab descendants of muhammad are regarded as übermensch or master race. Muslims of other ethnicity are below Arabs as demonstrated by Pakistanis in full vigour. Muslim hierarchy is Syed Arab>Arab>Persian>Turk>SE Asian>South Asian>Negro African.
A non-Arab by accepting Islam is also tactically accepting his place in Islamic social order, which is beneath Arabs. It is willful acceptance of slavery on part of a non-Arab muslim.The subservience of Pakistan to Saudi, even though having better military,higher population, and more diverse economy is a proof of that.
Another threat posed by muslims is that of security. While i am 100% sure that majority of muslims would side with India, if India goes to war with Pakistan, Bangladesh, or most of major muslim nation; i am also quite confident that if a true Islamic army led by a Caliph shows up on India's doorsteps (Bin Qasim type), most of muslims would side with Ghazis and turn on India ( this is true in case of Indo-Saudi war today ).In former case the choice was between India and a Muslim
nation while in latter case it is between India and Islam.This may sound politically incorrect but it is true.
Similarly Christianity ,at least protestant and Roman Catholic, is a vehicle to white imperialism. I would prove my case by using South Korea as an example. South Korea ,since converting to Christiantiy, has started worshiping whites, literally. It is a country in which practically everyone wants to have plastic surgery in order to look white.
Christianity, even though i could not speculate whether it is cause or symptom, has left Koreans with strong case of inferiority complex; a curious case in which they look for outside approval in order to define their identity, much like Pakistanis.Probably 200 years from now they, along with Philippines, would become Christians on Par with Nordics( who too were late converts), but as of today their position is low in christian pecking order.
When i say that India should remain majority Hindu, even if just nominally/culturally,i do it because i want India to avoid fate like Korea or Pakistan ( personally i am not religious at all ).I believe that every country should stick to their native religion, so while i believe that Islam is bad for India , i also acknowledge that it is best religion for Arabs.Persians recognized it and started their own version of Islam while Christianity transformed itself into European religion by integrating itself with Roman cult of Dionysus.