It's worth studying where the origins of the Hijab lie. Persian women long before Islam, wore a head scarf as a show of status. I don't believe there is anything specific in the Quran that suggests a woman should cover her head completely. There may be a vague suggestion that a scarf should be worn, but even this is very doubtful.
Could you show us from the Quran is which Allah made hijab compulsory?
The reason that Muhammads wives covered up was because they were being spat on and it was suggested to Muhammad that it might be better if His wives were covered.
There is much to do with modesty by both men and women. The hijab and the burqa a male inventions. The Prophet said only that a woman should wear a jalabib, loose covering clothes so that they did not fit to the body.
As for nun's, this is a human construct and is no part of Christianity. In ancient days it was a means of giving poor young women a safe refuge. Nuns tend to be be nuns by choice. Muslim women do not have so much of a choice because the peer pressure to conform is so strong, it is the law of the land and in countries like Australia, husbands demand it to show that their wives are compliant to the old ways.
Jews who wear the big hats, have long beards and wear their customary cloths and their women who also do not show their hair in public by wearing wigs or head scarfs are extremist, so you both have something in common.
