Really when was Christianity so prefect and so Islam.what relation it has conversion. it's like saying that suppose that your child is born you loved him cared him for long but later you find that he is mentally challenged so what will you do throw him out for new one just because it has one weakness.Caste system was indeed was very old system with feudal mentality you have to accept but it was effectively run since any long system presented In human history and that preserved our cultural identity since 5000 years many civilizations like egyptians, Greeks, Romans, are faded in ashes but we are still standing.There many reformers born with time before two mention. Please once again I tell just do some genuine research on our history not only from one angles but from all sides. Just suggestions read vivekananda.