Karl grew up in New Hampshire and became a Christian through the ministry of a Presbyterian church youth group. During college, he was a student leader with InterVarsity Christian Fellowship and got his first taste of missions through a short-term trip to Poland. Following graduation, Karl briefly worked for a publishing company before heading to Thailand for two and a half years to teach English and aid with evangelism and discipleship as part of an OMF church planting team. Karl earned a Masters of Divinity (M.Div) at Gordon-Conwell Theological Seminary and a Master of Theology (Th.M) at Talbot School of Theology, Biola University. In 2017, he began research for a Ph.D in World Christianity at the University of Edinburgh. Karl is an ordained minister in the Presbyterian Church in America (PCA).
Sun and her family fled from the killing fields of Cambodia and arrived as refugees in California. Sun heard the Gospel in Sunday school and later prayed to receive Christ. After high school, Sun sensed the Lord calling her into missions and pursued a degree in Biblical Studies from Biola University. Following graduation, Sun went on a short-term mission trip to Cambodia and then taught elementary school for a few years before returning to Asia to teach English in Laos. During her four years in Laos, she also earned an M.A. in TESOL through Azusa Pacific University. After Laos, Sun sensed God leading her to a very large Asian country where served for two years. Sun and her team shared the Gospel with top university students and partnered with churches.
Karl and Sun were married in 2005 and have three children, Joshua, Caitlin, and John. They did church planting ministry in Central Thailand during their first missionary term and then moved to Bangkok where Karl teaches part-time at Bangkok Bible Seminary, assists with editing and translation of Thai Christian books at Kanok Bannasan (OMF Publishers Thailand), and they are both involved with Grace City Bangkok, a new church plant in downtown Bangkok.