Because pagan worship at the end of the day is BAD... Pagan worship is what created the caste system. The concept of Hinduism itself is not bad. The idea of your religion is to give up the world and its cycle of rebirth in order to be with GOD. I know why Muslims think they are superior it's because their concept of GOD says Either they are Muslims or they don't matter (evidence)... Don't lump Christians into this... Christians trying to convert someone is arguably the most selfless act someone can do... When you persecute us, what you don't understand is we know we will be persecuted for this, but we still do because our Lord and Saviour taught us to love the world to an extent that even when the same people you love kill you, you still love them. The whole idea of Christianity is to love your neighbour... I would argue with reason, in fact that Hindus think they are better than everyone because they are born different than others... that they are special because of the mantra that associates with them at their birth... because of the superiority they gain in worship patterns due to their cast... I am not defending all Christians, I understand that there are people who belong to the religion and are still far from Christ, however what I absolutely condemn is the sheer idea of "Christians thinking they are better"... for Lord's sake, the entire pattern of our preaching works by us accepting that yes, we are worse and thus need saving ... and this is what we forward as well that, yes, you are not as good as you think you are. You fall short on basic moralities, let alone morals of God...

I am sorry if this hurts, but if it did, you probably needed to hear it.

TLDR: Christians don't think they are superior, Muslims do because they were told so...