Sam, a native of Park Ridge, Illinois, graduated from Northwestern University where he met Lois at a missions prayer group. He has degrees from Fuller, Princeton and Westminster Seminaries. Sam was ordained in 1966 and has pastored Presbyterian churches in Birmingham, Alabama and Aliquippa, Pennsylvania. Lois, the daughter of a minister, grew up in Michigan. She has degrees from Azusa Pacific University. Her ministry includes music, Bible studies, discipling women and coordinating a master’s degree program for Azusa Pacific University in Chile.

The Mateers began their mission career in Quito, Ecuador in 1981 where Sam served as team leader as well as participating in the founding of three churches. In 1988 Sam was appointed team leader of the Santiago Church-Planting Team in Chile and now serves as country director. They have been part of founding two churches, Cristo Rey and San Marcos, and are helping to form the first presbytery.