Free Thinkers
The 2nd Congress was held in September 1903 in Amsterdam under the title "Congress of Religious Free-thinkers." Sixteen countries were represented and 900 persons enrolled as paying members. V. R. Shinde of India represented the Brahmo Samaj, and Z. Toyosaki attended on behalf of liberal religious movements in Japan.

In 1904 the proceedings of this Congress were published under the title, Religion and Liberty. The Council held its 3rd Congress in 1905 in Geneva. Liberal Roman Catholics as well as Protestants participated in this "Congress of Religious and Progressive Christians," and European newspapers carried over four hundred reports of the meetings. The five religious services of the Congress, which were conducted in French, German and English, were held in the ancient Cathedral of St. Peter.
In 1907 the Council returned to Boston to hold the "Fourth International Congress of Religious Liberals," and 2,391 individuals paid the registration fee in order to attend. Official delegates were received from 88 religious associations and 33 separate church fellowships.
Affiliated societies included Unitarian, Universalist, free and liberal Christian, and free religious groups in Europe, North America, Japan and South Africa, and the Brahmo Samaj and Arya Samaj in India. Rabbi Charles Fleischer of Boston addressed the Congress, and M. Barakatullah of India presented a liberal Muslim perspective. Julia Ward Howe of Boston and Booker T. Washington of Tuskegee, Alabama also spoke to the Congress.Samuel A. Eliot, president of the American Unitarian Association and also the president of the Council, opened the Congress by proclaiming: "The significance of this gathering is that it is composed of men and women who in the pursuit of truth and righteousness dare to commit themselves unreservedly to the control of the law of liberty." Eliot appealed to "conscience, reason, and experience" and called upon the "Brethren of the Liberal Faith" to unite as "pioneers of pure religion and perfect liberty" in order to bring peace to the earth.