He opposed both James II's declaration of indulgence and Monmouth's rising, and he tried in vain to save from death his nonconformist brother John Hickes (1633-1683), one of the Sedgemoor refugees harboured by Alice Lisle.
[2] After remaining some time in concealment in London, he was sent by Sancroft and the other nonjurors to James II in France on matters connected with the continuance of their episcopal succession; upon his return in 1694 he was himself consecrated suffragan bishop of Thetford in the non-juring church.
His chief writings in this vein are the Institutiones Grammaticae Anglo-Saxonicae et Moeso-Gothicae (1689), and the celebrated Linguarum veterum septentrionalium thesaurus grammatico-criticus et archæologicus (1703–1705).
His two treatises, one Of the Christian Priesthood and the other Of the Dignity of the Episcopal Order, originally published in 1707, have been more than once reprinted, and form three volumes of the Library of Anglo-Catholic Theology (1847).
[2] Bishop Hoadly attacked the high-church views of Hickes in his "Preservative Against the Principles of the Nonjurors" and in his famous 1717 sermon "The Nature of the Kingdom of Christ".