He was the son of Thomas Sadler, unitarian minister of Horsham in Sussex, and was born there on 5 July 1822.
He entered the Unitarian ministry at Hackney, but migrated in 1846 to become minister of Rosslyn Hill Chapel in Hampstead, London, where he stayed for the remaining 45 years of his life.
He died at Rosslyn Manse on 11 September 1891, and was buried on the 16th on the western side of Highgate Cemetery.
[1] In 1859 Sadler published Gloria Patri: the Scripture Doctrine of the Father, Son, and Holy Spirit, in which he defended the Unitarian position against the views expressed in Rock of Ages by Edward Henry Bickersteth.
With some devotional works, Sadler was also author of Edwin W Field: a memorial sketch, 1872;[2] The Man of Science and Disciple of Christ, a funeral speech for William Benjamin Carpenter, 1885; and Prayers for Christian Worship, 1886.