His great-grandfather and grandfather were successively rectors of Penegoes, Montgomeryshire, and his father, who was educated at Balliol College, Oxford, was minister at Oswestry, Shropshire, from 1648 to 1662, when, refusing to subscribe to the Act of Uniformity, he was ejected, and went to reside at Wrexham.
While living there he is said to have read the whole of the five folio volumes of Matthew Poole's Synopsis Criticorum in Latin, and the works of all the Christian writers of the first three centuries after Christ, under the tuition of James Owen.
He was dissuaded from accepting it by Dr Daniel Williams, who, while advising him to stay at Wrexham, offered, rather than let him leave the country, to take him as his assistant in London.
He was an eloquent and popular preacher, and held in high esteem by his congregation, who in 1729 built for him a new chapel in New Broad Street, Petty France, Westminster.
In addition to his sermons he published his side of a correspondence with Dr John Cumming, "concerning the regard which ought to be had to Scripture consequences" (1719 and 1722); and illustrated with notes the Epistle to the Romans for the New Testament Commentary left unfinished by Henry.
He had formed the plan of writing a comprehensive history of nonconformity from the Reformation to the civil war, and collected the necessary materials at great expense.
He read, as he believed, almost every book in any way bearing on the subject, and commenced to write out his work, but he had not finished quite a sixth part of the three folio volumes which it was to occupy, when he was seized with his last illness, and the fragment was never published.
Evans possessed a very fine library, amounting to ten thousand volumes, which was sold by auction on his death to make a provision for his penniless widow and daughter.
It was generally believed that his daughter was an heiress, so well did he keep up appearances, and though certain members of his congregation helped him with money, the cause of his poverty remained secret till after his death.