During a visit to Morocco in 1817, Quilliam became interested in Islam when he saw some Moroccans praying during a break. He said of the day: “The ark was swaying , the wind was blowing , but they were not flinching. I was very surprised to see them praying like this. The tranquility of their faces was a testament to their unwavering faith and loyalty to the Creator. He stayed in Morocco for a while and learned about Islam. Then , at the age of 31, he converted to Islam. He said of his conversion to Islam: "Islam has no conflict with my own beliefs. Rather there are many similarities. So it seemed very reasonable to me to accept Islam. After converting to Islam, he changed his name to Abdullah Quilliam. He was the first person of the Victorian era in the United Kingdom to convert from Christianity to Islam. After returning to the country in 18, he founded the country's first mosque and Islamic center, the Liverpool Muslim Institute, in Liverpool. Liverpool was then considered the second largest city in the British Empire. In 189, he authored a book, The Faith of Islam, on the propagation of Islam and its principles. The book sold 2,000 copies very quickly and 3,000 copies the following year . Queen Victoria collected her writings, The Faith of Islam, and ordered six more copies of the book for her family members. The book was translated into 13 languages. He was also involved in publishing two fortnightly and monthly magazines, The Crescent and Islamic World. In 1890 he took part in a protest against the screening of Hall Cain's controversial play Mahomet. In 1891 , he attended a prayer service for a converted Muslim named Michael Hall , a Protestant preacher. Michael Hall converted to Islam in 1890. His funeral was the first public prayer in Liverpool. In 1894, with the permission of the British Queen, the Ottoman Sultan Abdul Hamid II granted Quilliam the title of ' Sheikh-al-Islam ' or ' Leader of the Muslims ' of the British Isles. He attended the opening ceremony of the Shitta Bay Mosque in Lagos, Nigeria that year. In 1896 he opened the Medina Home for unwanted children. The then Emir of Afghanistan called him the leader of Britain's Muslims and he was appointed vice consul of the Shah of Iran in Liverpool. As a result of his da'wah activities, many British people converted to Islam. Notable among them are Professor Nasrullah Warren , Professor Haschem Warren and Stalebridge Mayor Riched P. Stanley. As a result of his actions, about 600 non-Muslims in the United Kingdom were converted to Islam. Abdullah Quilliam worked for the rights of the underprivileged. He was vocal about trade unions and the right to divorce. Her career as a lawyer was threatened when she went to help a woman divorce her naughty husband. He was also getting a trap to catch the woman's naughty husband in handcuffs. This was very common in the case of British lawyers at that time. But when their strategy fails , Quillium finds himself trapped . He then left Liverpool in 1906 to avoid controversy and moved to Constantinople (now Istanbul). He returned to the United Kingdom in 1914 under the name Henry Mustafa Leon. He died on 23 April 1932. He was buried in Brookwood Cemetery, Oaking, London, on the 27th of that month.