With regard to one of your answers, I would like to raise a point that if we pay interest to buy an apartment or other necessary items, it implies that we are not against the system of interest; and with the passage of time, all those who were reluctant before to take interest and to become part of the system would have no problem with the interest-based economic system which is totally against Islamic directives.
In my opinion, the system can only be changed/modified, if we keep from being part of this system.
If paying interest were a sin, then the Qur’ān would have first of all asked Muslims to refrain from it – which it has not. In the absence of such a directive, we cannot stop people from paying interest. Also, the question is: in a society which is based so heavily on interest can staying away from paying interest really effect the situation? Can we live in isolation and can every Muslim be denied basic necessities on these grounds? If you do not want to become part of the system you can stay away from it, but don’t you think that this choice must be left to every Muslim.