He arrived at the English College, Reims, 25 May 1583, and received tonsure from Cardinal Louis de Guise on 23 September following. He left for Rome, 27 March 1590, where he was ordained priest, and was sent on the English mission in April, 1592.
He seems to have been a prisoner at Wisbech Castle, Cambridgeshire, when he signed the letter of 8 November 1598, in favour of the institution of the archpriest, and the letter of 17 November 1600, against it. Later he worked in Lancashire, where he was arrested by William Stanley, 6th Earl of Derby, and was committed to Lancaster Castle.
There Roger Wrenno, a weaver, was confined. They managed to escape one evening just before the Lent assizes, but were recaptured the next day. After that he was imprisoned with thieves, four of whom he converted. These were executed with Thulis and Wrenno. Thulis was hanged, drawn, and quartered; the quarters were set up at Lancaster, Preston, Wigan, and Warrington. Wrenno was hanged next, and, the rope breaking, he was once more offered his life for conformity; but he ran to the ladder and climbed it.
A metrical account of their martyrdom, as well as portions of a poem composed by Thulis, were printed by John Hungerford Pollen in his Acts of the English Martyrs (London, 1891), 194-207.