He was a member of the Christian Social People's Party (CSV), whose group he led in the Chamber of Deputies from 1 March 2011 until his sudden death six months later.
From 1967 to 1979, Thiel was the editor of Revue, before becoming the editor-in-chief of d'Lëtzebuerger Land: a position that he held from 1980 to 1989.
[5] He took a significant interest in economic matters, particularly the protection of pensions and responding to the 2007–2008 financial crisis.
[3] He was elected President of the CSV's group in the Chamber of Deputies in February 2011,[3] replacing Jean-Louis Schiltz when he stepped down on 1 March 2011.
As well as his political and journalistic work, Thiel was socially active, founding the Kräizbierg Foundation for the disabled, of which he became Chairman in 2011.