In 1767 he was appointed to the charge of Mill Hill Chapel at Leeds, where he again changed his religious opinions from a loose Arianism to definite Socinianism and wrote many political tracts hostile to the attitude of the government towards the American colonies.
It may be added that after the Reformation Arianism was revived in Socinianism, and Pelagianism in Arminianism; but the conception of heresy in Protestantism demands subsequent notice.
Arianism, when favoured by the reigning emperor, showed itself even more intolerant than Catholic Orthodoxy.
His views on the problems of Arianism, and his attempt to reconcile it with orthodox theology, are contained in A Specimen of True Philosophy (1730, reprinted in Metaphysical Tracts, 1837) and Logology, or a Treatise on the Logos in Seven Sermons on John i.
In 356 he went to Alexandria with Eunomius in order to advocate Arianism, but he was banished by Constantius.