In 1712 George Hickes was the only survivor of the nonjuring bishops, and in the next year Collier was consecrated.
He became tutor to the son of Sir William Hickes, and was eventually glad to accept the patronage of William Pierrepont, earl of Kingston, whose kindly offer of a chaplaincy he had refused earlier.
It was, however, no doubt at his wish that his chaplain wrote the Life of Julian the Apostate, in reply to Dr Hickes's sermons, in which the lawfulness of resistance in extreme cases was defended.
In 1716, in reply to George Hickes, he published a Preservative against the Principles and Practices of Nonjurors in Church and State, and in the following year preached before the king his famous sermon on the Kingdom of Christ, which was immediately published by royal command.
Hickes, whose chief argument, based on the character of the language, is now known to be fallacious, as most of the poetry that has come down to us in the West Saxon dialect is certainly of Northumbrian origin.