Born in Saarbrücken-Altenkessel, he entered (1901) a newly opened minor seminary in the SVD house at St. Wendel. He completed his further education at the SVD Missionary Major Seminary (St. Gabriel; 1908-1913) and was ordained a priest (1912). Appointed to a newly opened SVD mission in Portuguese East Africa (Zambezi), he worked among the Atchwabo people and began researching their culture. As a citizen of a country which was at war with Portugal, he was interned by the Portuguese (1916) first in East Africa, then in Portugal. After his release, he went to Steyl and worked there on the editorial board of the SVD missionary magazine Stadt Gottes (1921-1922). He began his studies (ethnology, study of religion, linguistics) at the University of Leipzig (1922-1924) and completed them, defending his thesis “Initiation Ceremonies of Girls at the Atxuabo (Portuguese East Africa)”. Already during his studies, he worked as an editor of Anthropos (1922-1931) and teacher at the SVD Missionary Major Seminary (St. Gabriel) (1922-1924). He helped W. Schmidt in the organisation of the Word Mission Exhibition in Rome (1925) and when the collection of objects presented there was turned into Pontificio Museo Missionario-Etnologico Lateranense (1927), Schulien was appointed the vice-director of the new museum. In fact, he was commissioned with day-to-day running it, as W. Schmidt, the director of the museum, only visited Rome. In 1939, he was appointed the director of the museum and held that post until his death in 1968. He taught ethnology and the history of religion at the papal universities in Rome (Lateran and Urbanianum) and founded Annali Lateranensi, an academic ethnological yearbook (1937; renamed as Annali del Pontificio Museo Missionario-Etnologico in 1962).
Schulien also carried out academic and diplomatic duties as an official of the Roman Curia.