Complex sentence: Søren Aabye Kierkegaard (or;) (5 May 1813--11 November 1855) was a Danish philosopher, theologian, poet, social critic, and religious author who is widely considered to be the first existentialist philosopher.
Split into simpler sentences: Søren Aabye Kierkegaard (or;) (5 May 1813--11 November 1855) was a Danish philosopher, theologian, poet, social critic, and religious author. He is widely considered to be the first existentialist philosopher.