Secondly, even if it says so, there is nothing that prevents a Hindu from following his own conscience. Hindus are not bound by absolute belief in any one book, like I said above.
Yes, many kings and emperors have killed millions. But they did not do so to propagate the only true religion - which of course would be the religion they followed. It is only Islam that gives a mandate for aggression for the spread of belief in its own claims. Those who take its teachings seriously, become what others called extremists - when it is these extremists who truly understand what the religion says and implement it.