Pretty much the same what I have said earlier.
But there is a geographical difference.Islam spread in North and west maninly because of conquests and the prime reason being the main access to West,North and Central Indian subcontinent was through land and invaders could thrust in to this part of the world.Whereas ,the downsouth ,having the cushion of deep Central land territory offered access mainly through waters and none of the invading forces had ventured out for that.This is one of the main reasons ,the foreign religions such Islam,Christianity and Judaism arrived in down south through traders.
The communal harmony and the friendly nature existed with the people of down south was one of the main reasons,Judaism suffered absolutely no harm at the hands of local people ,though it had suffered in other parts of the world.After the modern state of Israel became a reality in 1948,many of the Jews who had lived in Kerala had left for their promised land but a handful of the families chose to stay back.(Just abt 48 families).
Again as for Christianity,it is believed that the first converted person was Brahmin ,by St.Thomas.
One of the incrdible things is,many Muslim families in kerala do take part in some of the Hindu festivals ,as part of their ancestral roylty .I have personally seen Muslims doing their offerings to some of the prominent temples in kerala.But this piture becomes bleak and different when it goes to North.I believe they are some more conservative.