A fascinating and disturbing insight into the mindset of Islamic State is provided in an Arabic document that advocates marriage for girls at the age of nine, and says Muslims must not study worldly sciences.

The text, a piece of propaganda aimed at Arabic women and laced with references to Islamic scripture, states that it is the "divinely appointed right" of women to have a sedentary lifestyle.

Marriage can be from the age of nine, it says, after which girls and women must remain "hidden and veiled". The document implores women in Saudia Arabia to leave for IS "urgently".

It adds that Muslims must not study the sciences because they give "no spiritual reward".

The document, entitled Women in the Islamic State: Manifesto and Case Study, was uploaded by the all-female Al-Khanssaa Brigade's media wing onto a jihadist forum used by IS. It was distributed among Arabic-speaking supporters of the extremist group.

At more than ten thousand words long, it calls on women who have not joined IS to push their sons to join up so they can help build the foundations of the Caliphate "with their skulls".

It criticises Muslims who have friendly relations with the "infidels" who are at war with IS.

The model for women preferred by infidels in the West failed the minute that women were "liberated" from their "cell" in the house, the manifestor says. "Problems emerged one after another after they took on corrupted ideas and shoddy-minded beliefs instead of religion, Shariah and the methodology of life that was ordained by God."

Girls should be educated, but from the age of seven to 15 only, and mainly in religion and skills such as knitting and cooking. Fashion and beauty shops are the work of the devil, it says.

The document shows what IS thinks of Western efforts to combat it. "The soldiers of the Antichrist come every day and the hum of their jets can be heard as they come to throw bombs from the skies and demolish buildings."

It particularly condemns the "westernisation" of women in parts of the Middle East where "female dignity has been obliterated" and "women are able to work alongside men in shops like banks, where they are not separated by even a thin sheet of paper."

Haras Rafiq, Managing Director of Quilliam, said: "There has been a huge amount of speculation about what the role of the women who join Islamic State – often dubbed jihadist brides – is. This translation by Charlie Winter clarifies a number of issues that have been obscured by the language barrier until now. It allows us to look past the propaganda banded about on social media by Western supporters of IS, enabling us to get into the mind-set of the hundreds, perhaps thousands, of women who willingly join its ranks."

Quilliam researcher Charlie Winter, who translated the original document, told Christian Today that the report cut through a lot of the rhetoric of English female jihadists. "They talk about excitement and a life of adventure. The document shows that IS women do not have a life beyond mother and wife. They might leave the house for work if a teacher or doctor."

Women can also leave the house if needed for jihad, it says. "But for most the primary responsibility will be raising the next generation of jihadists and putting food on the table," Winter said. Quilliam's latest estimate, based on social media, is that about 50 British women have left to join IS in Syria.

Maryam Namazie, of the Council of Ex-Muslims of Britain, said: "The IS Women in Islamic State manifesto doesn't tell us anything new. The views of the religious-right in general and Islamism in particular on women is always misogynist and sees females only as organs for religiously-permitted reproduction. Otherwise, they are there to be covered up, kept silent, uneducated, and used as vehicles for male gratification.

"The IS manifesto is a prescription for women's continued oppression under Islamist rule – one that is challenged by many women and men, including Muslims across the globe."