[1] She graduated from Barlaeus Gymnasium in Amsterdam and decided to follow in her father's footsteps, pursuing her university studies in theology.

[2] In 1916, she presented her dissertation on the Dutch dogmatic Lutheran theologian Franz Hermann Reinhold von Frank (De Theologie van F.H.R.

She also began preaching in various municipalities for both the liberal branch of the Dutch Reformed Church and the Netherlands Protestant Association.

[5][2] Bruining publicized their approach both in their broadcasts and in the articles frequently published in the radio magazine Vrije Geluiden (Free Sounds), advocating non-sectarianism and inviting all intellectual movements to participate.

When one of her students, Elisabeth Waisvisz and her family, were threatened with deportation, Bruining acted as an intermediary with the underground to help them find safehouses, provided ration coupons, acted as a go-between for delivering letters between the family members and personally delivered the message to Waisvisz that her parents had been betrayed and sent to Westerbork transit camp.