Frederick Sinclaire was born and educated in New Zealand. After receiving an MA he studied theology at Oxford University with the financial support of the Unitarian Church. Posted to Melbourne as a minister of the Unitarian Church, he became well-known for his socialist views, opposing other clergymen on issues such as prostitution, drinking and gambling by arguing that these were social not moral problems.
Involved with the Victorian Socialist Party and Melbourne's Fabian Society, Sinclaire became acquainted with other socialists such as Bernard O'Dowd, Vance Palmer, Louis Esson and Frank Wilmot. His association with socialist groups was tolerated by the Unitarian Church, but members objected when he began to host meetings of the Fabian Society on church property.
In 1911 he left the Unitarian church, but was encouraged to stay in Melbourne by a group of followers who later formed the Free Religious Fellowship and financed a small salary to support Sinclaire as minister. Sinclaire co-edited the Socialist with Marie Pitt in 1911 and 1912, before the Free Religious Fellowship established its own magazine, Fellowship, in 1914 with Sinclaire as editor.
Many of Sinclaire's socialist friends contributed to Fellowship, producing a magazine that challenged orthodox religion and the classicism of university-based literary criticism. Vance Palmer, in particular, published many articles advocating a wider acceptance of Australian literature. In addition, he objected to the detrimental effects he believed the suburban modern nation was having on 'traditional' Australian culture. Sinclaire continued to argue in Fellowship that socialism was a better reflection of Christian values than orthodox religions and adopted anti-imperialist arguments that situated creative growth within Palmer's nationalism. Claiming workers as an important element of this growth, Fellowship supported striking railway workers and opposed conscription during the First World War.
In addition to Sinclaire and Palmer, other contributors included Nettie Palmer, Frank Wilmot, Bernard O'Dowd, J. Le Gay Brereton and Frederick Macartney. Fellowship ceased production in 1922.