In 1680 he received the degree of Doctor of Divinity, and was presented by King Charles II to the important London church of St Martin-in-the-Fields. Tenison, according to Gilbert Burnet, "endowed schools including Archbishop Tenison's School, Lambeth, founded in 1685 and Archbishop Tenison's School, Croydon, founded in 1714, set up a public library, and kept many curates to assist him in his indefatigable labours". Being a strenuous opponent of the Church of Rome, and "Whitehall lying within that parish, he stood as in the front of the battle all King James's reign". In 1678, in a "Discourse of Idolatry", he had condemned the heathenish idolatry practised in the Church of Rome, and in a sermon which he published in 1681 on "Discretion in Giving Alms" was attacked by Andrew Poulton, head of the Jesuits in the Savoy. Tenison's reputation as an enemy of Romanism led the Duke of Monmouth to send for him before his execution in 1685, when Bishops Thomas Ken and Francis Turner refused to administer holy communion; but, although Tenison spoke to him in "a softer and less peremptory manner" than the two bishops, he was, like them, not satisfied with the sufficiency of Monmouth's penitence.