Arborelius was born on 24 September 1949 in Sorengo,[1] Switzerland, to Swedish parents, and grew up in Lund in Scania.

[4] At first, following his conversion, he desired to be a diocesan priest, but, after reading Saint Thérèse of Lisieux's autobiography (The Story of a Soul), he wanted to be a member of the Discalced Carmelites.

[4] In 1971, two years after he became Catholic, he entered the Carmelite order at the Norraby monastery located near the town of Rydebäck in Southern Sweden.

[1] After obtaining his doctoral degree at the Pontifical Theological Faculty Teresianum in Rome, he was ordained as a priest in Malmö on 8 September 1979.

[8] He said he thought Francis was recognizing Sweden's role in accepting immigrants and promoting interdenominational dialogue.