I feel you should look at the census figures during the british period and y will be surprised to learn that the muslim population in India ( other than the pakistan bangladesh areas)increased in that period more than during any other historic times. this shows voluntary conversions taking place all the time mainly during the last 150 years The problem with other communities/religions trying to castigate islam is that they themselves are coming nearer to it in their practices in terms of becoming more organised in worship practices and core unity of believers as compared to their earlier personal religious practices. regards rajeev phanse
