ejazr,
when the taliban were ruling afghanistan then what was their take on this, as in did they consider everyone excluding wahabis/sunnis as kafir (assuming most of them are wahabis/sunnis if i am not wrong) and how was their way of dealing with shias, ahmedis, etc different to what they meted out to their wahabi/sunni counterparts?
Well I personally think that understanding this from a politcal rather than religious makes more sense. In other words, anyone that can challenge my politcal power, declare them Kafir. So the shias in Afghanistan i.e. theHazaras were targetted, so were the Sunni Tajiks and Uzbeks. There are no Ahmedis in Afghanistan but one of the reasons to target Ahmedis was that they are closet Zionists and spies of the US e.t.c. in Pakistan. Again a political angle mainly with the religious angle acting only as a justification. Similarly Shias in Pakistan are on average better off in Pakistan with most ofthem educated and in the beuracracy. A shortcut of disempowering the shias politcally or otherwise is to declare them Kafir and ready to be killed. If you read their (extermists anti-shia groups) literature, they actually talk about conspiracy theories of how pakistani shias are in cahoots with the Americans to destroy Pakistan. Again a politcal angle. It doesn't help that other than Nawaz Sharif and Zia most of the rulers/PMs that Pakistan had were shias.
Infact, you will be surprised that Afghan Hindus and Sikhs actually had a better time under the Taliban according to a recent Reuters report I was reading. Because they tended to follow the requirements of granting protection to non-muslims in their land under their control.
let us take the extreme example and say tomorrow sometime in the future the ttp were to rule pakistan, would they be the exact same to their counter parts in afghanistan, the taliban? how different are they ideologically?
Ideologically TTP are very different from Afghan Taliban. Operationally they are quite different as well. IF you go by the reports, TTP leadership is heavily dominated byPunjabi extremists and AQ Arabs, the foot soldiers may be Pashtuns. However, the Afghan Taliban are Pashtoons from top to bottom. And atleast less extremist than TTP. Espicially if you look at the suicide attacks.
TTP is way more dangerous ideologically than Afghan Taliban.
why and when did the concept of kafir originate, and what was the exact purpose of having it?
why do the moderates call these extremists as non-muslims? is it a way of distancing with their violent path?
Kafir or Kufr means rejector (of faith), it does not apply to all non-muslims first of all. And even if someone is a Kafir, it doesnt mean they should be killed e.t.c.
But I assume that you are more interested in the concept of Takfeer i.e. declaring other muslims Kafir.
There are many theories but speaking in the current scenario, it was Maududi and Syed Qutb who came up with the idea of declaring people particularly Rulers as Kafirs and hence liable fordeath. Later Zawahiri and other extremists extended it to the people as well. Thereis a very interesting documentary "The Power of Nightmares" that woudl be helpful and I highly recommend people to watch it.
Common-history-of-the-neo-con-and-the-Islamists-movement-BBC-Documentary
On your second question, yes, I think the average muslim is so disgusted by these actions that there is a denialbut more so a rejection that such an action can not be of a muslim and even if was born as a muslim, he has thrown himself out of the fold of Islam by committing such an act.