Treur grew up in a strict Reformed Christian farming family in her Zeelandic birthplace of Meliskerke. After secondary school at the Calvijn College, she went on to study psychology at Leiden University. Later she switched to Dutch language and literary science. In Leiden, she became a member of the Reformed student association Panoplia. According to a newspaper interview, during her studies she discovered the similarities between stories from Ancient Near Eastern cultures and those related in the Bible, which convinced her that such stories were merely invented to console human beings. Moreover, she says that she had never felt the existence of God, and therefore abandoned her faith, informing the board of Panoplia about it on 11 September 2001.