Islam, for me, is a way of life and the core of my world. As a Muslim woman I have always been encouraged to be who I want to be.

I get frustrated when people say: “Why do you wear a hijab? Isn’t that a sign of women’s oppression?” I choose to wear a hijab; I choose to be an educated and liberated woman and I choose to follow Islam.

Islam states that a woman’s purpose for existence is not to serve any other human beings or be subjugated by any other person.

I recently visited Niger, where up to 98% of the population is Muslim. The country also has the world’s highest child marriage rate, with three out of four girls married before the age of 18. Key drivers for this are poverty, local customs, tradition and lack of education.

Niger is the fifth poorest country in the world, and I saw for myself acute signs of poverty. I spoke to families who told me how they gave up their daughters for early marriage because they were struggling to feed or protect them, let alone send them to school. Girls suffer more than boys. Only 15% of women in Niger aged 15 to 24 are literate, compared with 30% of men.

In Loga, 140km east of the capital Niamey, I met Mariama*, who was given up for marriage at the age of 12. Traumatised, she escaped on the night of her wedding and fled to the house of Maimouna Djibrila, a volunteer working with Islamic Relief. She of all people understood what Mariama was going through. She too had been given away for early marriage to a cousin, and had a very difficult time.

Maimouna worked with several organisations, Mariama’s school, the police and both families to get the marriage annulled. Unfortunately, two years later (a month before our visit), her father was trying to marry off Mariama again.

Early and forced marriage is a contentious subject in Niger. The country has signed up to international treaties that set a minimum age of marriage of 18. However, the legal age of marriage is 15 for girls and 18 for boys. There have been ongoing discussions in parliament to make sure that the national law respects the international treaties, but this has not yet happened.

Mariah Idrissi during her visit to Loga, in south-west Niger. Photograph: Shaista Chishty/Islamic Relief

Even if the law changes, it is unlikely that child marriage will stop overnight. It is entrenched in the culture in Niger. I want to be clear on this: this is not an Islamic issue, but a cultural issue.

For any change to happen, it has to happen at community level. Islamic Relief is training community and faith leaders, such as Imams and village chiefs, about the importance of women’s rights and child protection.

Imams are vital in this campaign. I witnessed imams preaching about the rights of women and children in their Friday sermons, known as khutbas. They pointed out that the Qur’an states it is not lawful for men to inherit their wives by force, or for parents to let their children be harmed in any way. And how a successful marriage according to Islam promotes love, tranquillity and mercy between husbands and wives.

The latter is particularly important, given the high levels of domestic violence in the country. An estimated 15.6% of women experience some form of sexual violence or harassment.

I met Adama in Loga, who was raped by an extended family member when she was 15 and then ostracised by her family for giving birth to his child outside marriage. She was kicked out of the house while pregnant. Maimouna convinced Adama’s mother to help her, and now she too is being ostracised by the family. It was heartbreaking listening to Adama. She told me that she has been reduced to begging for food and is insulted every day. I could see the pain in her eyes as she recounted her story.

It infuriated me to see Adama treated in this way, and to see so many young girls being forced into early marriage. Allah commands us to protect the honour of women, and the Qu’ran clearly states that violence against women and girls, in any shape or form, is not acceptable. It is not acceptable in the UK; it is not acceptable in Niger.

Adama’s story and many others I heard in Niger have fired me up in support of Islamic Relief’s #HonourHer campaign, which is working towards a global Islamic declaration of gender justice – a call to action against gender inequality from an Islamic faith perspective – to be launched later this year. I will use my voice to play an active part in this.

Mariah Idrissi is a model and activist

* Name changed to protect identity