In 1926 at the age of 20, Marie joined the School Sisters of St. Francis, a religious order with a focus on teaching.

[1] Brenner later attended DePaul University and earned a bachelor's degree in social science.

At this time, a movement was stirring in religious circles that religion was not only about catechism questions and answers, but about loving one's neighbor no matter their race, ethnicity, or social status.

A famous line from Karl Marx states that "Philosophers have only interpreted the world, in various ways; what is important is to transform it.

As in Chicago, she encouraged students to engage in critical analysis of social issues in her classes at Alverno.

She assigned her students to investigate and report on the conditions of Chicago public housing, child care centers, Cook County prison and court facilities.

[1][6] In her classes at Alvernia, Brenner instructed her students about the spiritual, material, and physical disadvantages of the immigrant.

In particular, members of the School Sisters of St. Francis began to participate in demonstrations and activism on racial justice during the civil rights era.

They were the first group of Catholic women religious to play a leading role in a public demonstration on racial segregation in Chicago.