Saudi Arabia is the main sponsor of this. They fund a lot of such conversion programs and are equally loathed. Furthermore the version of Islam the Saudi-affiliated organizations spread is Wahhabi-ism, the most fundamentalist version of Islam. needless to say this might cause even more animosity.
Btw the conversion to Islam is pretty rare. I refrain from using the term low castes, but the low castes are given a lot of affirmative action benefits(almost 33% reserved seats in colleges and in government jobs).
The irony is that those who converted to Islam/Christianity are now asking for quotas in education/employment which the low castes are entitled to. Its the classic case of trying to both have the cake and eat it, as Islam and Christianity claim that they do not have any social class-differentiation! (as if the caste system is Hindu in the first place...but that's a topic for a diff thread).
I mentioned the Christian missionaries cos they are the most vocal ones, oft ranting against the "persecution" they face. In the light of the recent scandals involving missionaries a lot of the previous claims of the missionary organizations will have to be looked into in detail. I could hazard a guess that a lot of them might indeed be found guilty of illegal activities. Missionaries in general are highly disliked in India, and not without reason. During the colonial rule the vast majority of missionaries worked hand in glove with the occupiers and prospered under the auspices of the colonial powers.
The notion that one "way"(religion) is the only "true" way and everything else is wrong is anathema to the Indian psyche. The Dharmic religious worldview regarding other religions/philosophies is this.
"Ekam Sat, Vipra Bahudha Vadanti"
One Truth, Many paths
Thus, for the Indian mind, the claim that only one religion is true while everything else is wrong sounds like the worst form of ignorance/arrogance.Hinduism is not a missionary religion, and it has always welcomed people of myriad faiths and persuasions with open arms. The Jewish people found refuge in India After the destruction of their first temple. Yet more came when the Romans occupied Judea and later during the Spanish inquisition. Not only were they welcomed, but were given tracts of land to settle, where they live to this day without experiencing a single incident of anti antisemitism from their Hindu neighbors. The only two instanced the Jewish people of India faced antisemitism were when they were attacked by Muslims in the 17th century, followed soon-after by the infamous inquisitions by the Portuguese
http://en.wikipedia.org/wiki/Goa_InquisitionThe Zoroastrians too, were welcomed in India, and one of the largest surviving Zoroastrian community in the world is found in India. They came as refugees when Persia was invaded and taken over by the Islamic armies and have thrived in India. We even had a Zoroastrian head of state!
The main difference between the Jewish/Zoroastrian people who live in India, and the Islamic/Christian ones is that the former do not seek any converts. They live by themselves and are loved by their neighbors. Most Indian Christians and Muslims also follow this trend. However the "my way is the only correct way" mentality of Christianity and Islam also spawns/attracts Missionaries to India, and naturally this cases resentment. Add the fact that they come loaded with cash, and use it to persuade people to change religion is looked upon as a form of bribery, and worse yet, as exploitation of the poor. In light of this it's not too hard to imagine why people are against missionaries and missionary religions.