Arjun was fighting his own brother, this fight was not between two religion, this fight was between good and evil and that why Arjun was asked to fight, lord Krishan said that u must fight for the sake of goodness, so that goodness previl that is Hindusim dear. In Hindusim Truth and Justice is termed as the synonim of Religion not like other religion which directly ask his followers to kill other people who does not believe in u
and for Draupadi that was a expectional case and well it is better that taking wife a six year old girl
