Charles Strong (26 September 1844 – 12 February 1942) was a Scottish-born Australian preacher and the founder of the Australian Church. Strong was educated at the University of Glasgow, where he adopted a liberal and broad church theology under the influence of his mentor John Caird. After being ordained in the Church of Scotland and holding a series of Scottish ministries, he was selected as the new minister of Scots' Church, Melbourne, in 1875. Upon moving to Australia he was initially a popular and successful minister, but eventually began to attract criticism due to his liberal views. Facing a heresy trial, he resigned from the Presbyterian Church in 1883.

In 1885 Strong founded the Australian Church. The church quickly attracted a large following, particularly among Melbourne's economic, political, and intellectual elite. Strong was active in advocating for a range of charitable and political causes, including labour rights, prison reform, and pacifism. However, his increasingly radical preaching and the financial difficulties of his church eventually caused the Australian Church to decline, and in 1922 it sold its premises and moved to a smaller building nearby. Strong died in 1942 at the age of 97. The Australian Church continued for a time after his death, but eventually ceased to operate in 1957.

Strong was born on 26 September 1844 in Dailly, Scotland, to the Reverend David Strong and Margaret Paterson (née Roxburgh). Strong was educated at the Ayr Academy and Glasgow Academy, and studied Arts and Divinity at the University of Glasgow between 1859 and 1864. He was strongly influenced by the theologian John Caird, a leading figure in the philosophical movement known as British idealism, and came to hold a liberal and broad church theology.

After graduating from university, Strong became a private tutor to the son of Allen Thomson and travelled across continental Europe. He began ministering in the coal mining town of Dalmellington in 1868. In October of that year he was ordained in the Church of Scotland and began to minister in Greenock. On 16 March 1871 he was inducted to the church in Anderston, a suburb of Glasgow, where Caird was among his congregants. In 1872 Strong married Janet Julia Fullarton, who he had met while ministering in Greenock.

In May 1875 Strong was chosen as the new minister of Scots' Church, Melbourne; he arrived in Australia with his family in August of that year. Strong quickly found success as a minister, becoming popular among Melbourne's working class and successfully drawing many educated and disaffected congregants back towards religion. He served a term as moderator of the Melbourne Presbytery and was a member of the councils of Scotch College and Ormond College.

Strong's liberal views on theological matters, however, eventually led to suspicion from some in the Presbyterian Church. In 1880 Strong published a controversial essay titled "The Atonement" in the Victorian Review, which led the Presbytery to appoint a committee to investigate the article. His changes to the church's worship practices and his calls to reform the Westminster Confession of Faith also concerned his fellow clergy. In August he offered to resign from the church, but agreed to instead take six months of leave at the request of his congregants and church officials.

After Strong returned to Melbourne, he provoked renewed backlash by advocating for the opening of libraries and museums on Sundays. This was a popular cause among social liberals, who hoped to promote self-education among the working class, but was opposed by those who feared that it would undermine the sanctity of the Sabbath. In 1883, he invited the Chief Justice of the Supreme Court of Victoria, George Higinbotham, to deliver a lecture on the relationship between science and religion. Higinbotham's speech angered members of the church by suggesting that religions should become more flexible in their beliefs to keep up with modern science, and led the Presbytery to appoint another committee of inquiry to investigate Strong. Strong offered his resignation from the church in September 1883 under threat of heresy charges. On 15 November, as Strong embarked on his return to Scotland, the assembly revoked his status as a minister of the Presbyterian Church of Victoria.

During Strong's time in Scotland, he was offered ministry positions at various other Presbyterian churches. But he had lost his faith in the denomination, and resolved to found an independent church. In October 1884 he returned to Melbourne and began to minister to an independent congregation of around 800 people at the Temperance Hall on Russell Street. In November of that year he became the first minister of the newly founded Australian Church. The church built a lavish new building on Flinders Street, which cost £21,000 to construct and could seat 1500 congregants. It also featured what was the largest organ in Australasia at the time.