It's simple logic Dalli Resham...they do not believe in materialistic world...do not care about man made things...do not worry about clothes, tv, internet or movies...they believe that when god created the world...they created us nude and every animals are nude too..so there is no purpose of wearing clothes becasue god made us capable of countering the world and cold weather without wearing clothes...it was just US who made ourself more focued towards materialitic world for our own convinience. Its simple.