Sister Maria Theresia of the Most Holy Trinity

A Hidden Missionary of Quiet Suffering

Teresa Ysseldijk was born on November 13, 1897, in the Netherlands and raised in Germany. At nineteen she entered the Carmelite Sisters of the Divine Heart of Jesus, the congregation founded by Blessed Maria Teresa of St. Joseph, taking the name Sister Maria Theresia of the Most Holy Trinity. She professed vows on July 2, 1919.

That same year she sailed to the United States as one of seven Carmelite missionary sisters. After a short time at a convent in Wisconsin, she joined the community at St. Charles, Missouri, where the sisters ran homes serving the elderly and children.

Shortly after arriving she was diagnosed with advanced kidney disease. Despite surgery to remove a kidney, she could not be cured. She professed her perpetual vows amid declining health and became known in her community for the cheerful, hidden endurance of suffering; a fellow sister later summarized her motto in her final year as wanting to suffer quietly and to thank God loudly. She died on March 10, 1926, at St. Mary’s Hospital in St. Louis, aged 28, and was buried at Holy Cross Cemetery in Wauwatosa, Wisconsin.

Her cause was opened in 2010 in the Diocese of Roermond in the Netherlands, with the positio completed in 2021. On April 27, 2026, Pope Leo XIV recognized her heroic virtues, declaring her Venerable. Press coverage called her a little-known saint next door, and her community has announced plans to transfer her remains from Wisconsin toward St. Louis, the city where she died.

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