[2] In 1865 he entered the theological seminary in Chicago, where he graduated in 1868, and preached for three years thereafter as a Congregational minister in the pulpits of Illinois.

He attacked the Bible and Christianity upon the platform, and for 20 years probably making more speeches against them than any other American, speaking almost every day for months together.

Putnam was married to Louise Howell for eighteen years, they divorced in 1885 due to religious differences.

[2] Historian Leigh Eric Schmidt discusses Putnam's life in Village Atheists: How America's Unbelievers Made Their Way In a Godly Nation (2016).

His body was found on the floor with twenty year old lecturer May Collins in her hotel room in Boston.