Mary Christine Tan was born as Amanda on November 30, 1930 to an upper-class Chinese Filipino family in Manila.

She is the fifth amongst her seven siblings, for whom they are: Consuelo, Bienvenido Jr. (who became a member of the Agrava Commission and later the Ambassador of the Philippines to Germany), Teresita, Caridad, Leticia, and Angeles.

She graduated with the degree of Bachelor of Science in Mathematics, before joining the Religious of the Good Shepherd (RGS), and was given the name by which she is most recognized today.

[2] As mentioned in her own words, she describes these years to be a bit placid:[2] "[I couldn't] recall a single sorrow or problem or even joy that made any dent to the core of my being.

[5] On the outset of Martial Law in the country, Sister Christine became an outspoken political activist who fought for the restoration of democratic rights.

[2] Tan and the rest of the AMSRP members asserted liberation and respect for human rights along with "a weekly compilation of news suppressed by the martial law government".

[6] For 26 years, she and her RGS sisters lived in the Leveriza slum in Malate, Manila, where she was exposed to the reality of poverty and the prevalence of crime and drugs.

The broadsheet managed to get the responses of two of the six nuns who joined Tan in her mission, Sisters Vincent Borromeo and Evelyn Coronel.

[2] Following the aftermath of the People Power Revolution in 1986, Sister Christine was named a member of the Philippine Constitutional Commission of 1986 by President Corazon Aquino.

Her autobiography, which was centered on her story with the RGS congregation and the journey from Eastern Spirituality to Social Justice, was released to the public by her brother Bienvenido Jr. four days after her passing.