In 1954, Huldah and her late husband, Rev. Dr. Mark Buntain, agreed to travel to India and serve in Calcutta for one year. That year turned into a lifetime of service to the people of Calcutta and its surrounding communities. Together, they established a holistic inner-city outreach consisting of more than 100 schools, over 700 churches, a daily feeding program for 25,000, and a full general hospital that has treated 2.2 million people and provided free care to 880,000.

After her husband passed on in 1989, the Calcutta mission appointed her Chairman and Senior Pastor of the church. Since then, she has continued to faithfully serve the people of India as she travels around the world raising funds. In 2005, Huldah founded Calcutta Mercy Ministries to support the comprehensive ministry her and her husband built over the past 53 years.