Raymond Bates Buker, Jr., was born on December 26, 1925, in Lewiston, Maine, to Dorothy and Raymond Buker, Sr. His father had been pastor of three Baptist churches in Maine before his son was born. Before Raymond Jr. was a year old, the Buker family became missionaries and moved to Burma in 1926. Buker spent his childhood in Burma, and attended school in Taunggyi, Central Burma. His high school years were spent in Woodstock, India, after a hazardous journey across Japanese-occupied territory in 1941. It was during his studies at Woodstock that Buker made the decision to become a missionary himself. The Buker family returned to the United States in July 1942, when World War II made it too dangerous to stay in Asia.

Buker continued his schooling at Stony Brook High School, Long Island, New York, until 1944, when he entered Wheaton College. While at Wheaton, he headed the cross-country and track teams which were trained by coach Gil Dodds to win national meets. He majored in Anthropology and was President of the International Club. After graduation, he entered Gordon-Conwell Theological Seminary in Massachusetts, earning a Master of Divinity degree in 1950. While he was serving as a summer pastor in Maine, he met his future wife, Jean Mc Gregor, who was working her way through Providence Bible Institute. They were married after his graduation from seminary.

Buker made application to return to India under the Conservative Baptist Foreign Mission Society, partly because of his parents' connection with the Northern Baptist Convention and his father's work with Conservative Baptists in 1943. While waiting for a visa, he attended Hartford Seminary Foundation Kennedy School of Missions. Because visas were not being issued to India at that time, the Bukers were assigned instead to West Pakistan, arriving in Karachi in 1954. From there, Buker went to language school to learn the Sindhi language and, with his wife, joined three other mission families to settle in Larkana, located in southern West Pakistan.

Mission work included evangelization of Muslims, supporting and revitalizing the existing Christian churches in the region, developing Sunday Schools for children and women, education for literacy, correspondence courses, and Bible translation. The Bukers and others also cooperated with other missions to provide Bible schools, schools for missionary children, and production of literature. In addition to work with Muslims, the Bukers evangelized members of the Marwari tribal people, an outcast group shunned by the Muslims. Buker learned the unwritten Marwari language, similar to Sindhi, produced an alphabet, and translated the Gospel of John. He also prepared a hymn book and tracts.

During their first furlough in 1959, Buker returned to Massachusetts and then moved to Colorado to teach a course on Islam and engage in studies at Denver Seminary. The Bukers returned to Larkana, where they remained in the same types of mission work until 1969. Between 1970 and 1972 Buker assumed the duties of the Midwestern and Western campus representative for the Conservative Baptist Foreign Mission Society, working out of Denver. In 1972 the family moved to Wheaton, Illinois, and Buker became Personnel Secretary for CBFMS. In this capacity he worked to generate growth and interest in short term and life term missionary careers. He also processed applications, counseled applicants and children of CBFMS missionaries attending school in the United States.

The Bukers had five children: Merelyn, Carolyn, Stephen, Benjamin and Timothy. As of 1983 they lived in Wheaton, Illinois.