Background
Martensen was born in a middle-class Lutheran family in Flensburg, in the Duchy of Schleswig (now Germany), as their only son. He grew up in a German-speaking society, while his father who was a schoolmaster, writer and sea-captain preferred to use Danish.
Education
Hans Lassen Martensen studied theology in Copenhagen, and later was ordained in the Danish Church. Also he studied Dante"s The Divine Comedy with a great interest.
Career
At that time Schleswig was a duchy between Holstein and Denmark. Consequently the young Martensen upbrought in a multicultural situation and reconciliation of different cultures became his one of central interests through his life. From 1834 till 1836 he travelled foreign countries.
He visited several cities including Berlin, Munich, Vienna and Paris.
He met influential intellects including Hegel, David Strauss, Franz von Baader and Schelling. During his travel, he began to read mystics, Eckhart, Tauler and Boehme.
At Copenhagen he was lektor in theology in 1838, professor extra-ordinarius in 1840, court preacher also in 1845, and professor ordinarius in 1850. Once he was offered to a bishopric from Swedish Church but declined.
In 1854 however he gave up his educational career and was made bishop of Zealand, the Danish Primate.
Martensen died on February 3, 1884 in Copenhagen, Denmark. The Icelandic theologian Magnús Eiríksson (1806–1881), who lived from 1831 until his death in Copenhagen, was very critical of Martensen’s speculative theology, which he violently attacked in various publications from 1844 to 1850.