The result of this reading, and of the influence of John Wilkins, Master of Trinity College, Cambridge, was seen in the general tone of his preaching, which was practical rather than theological, concerned with issues of personal morality instead of theoretical doctrine.

This plain style of preaching is reflective of the late 17th century, when the integration of reason into Protestant theology came to be seen as one of its finest attributes against Catholicism.

Tillotson himself was personally tolerant enough towards Catholics, remarking in a famous sermon that while Popery was "gross superstition", yet "Papists, I doubt not, are made like other men".

The same year he married Elizabeth French, a niece of Oliver Cromwell; and he also became a Tuesday lecturer at St Lawrence, Jewry (where he was later buried).

In 1663 he published a characteristic sermon on "The Wisdom of being Religious," and in 1666 replied to John Sergeant's Sure Footing in Christianity by a pamphlet on the "Rule of Faith."

He afterwards enjoyed the friendship of Lady Russell, and it was partly through her that he obtained so much influence with Princess Anne, who followed his advice in regard to the settlement of the crown on William of Orange.

In August of this year, he was appointed by the chapter of his cathedral to exercise the archepiscopal jurisdiction of the province of Canterbury during the suspension of Sancroft.

His attempts to reform certain abuses of the Church of England, especially that of clerical non-residence, awakened much ill-will, and of this the Jacobites took advantage, pursuing him to the end of his life with insult and reproach.