An ordained elder in the Church of the Nazarene, Rainey served as a pastor in Houston, Texas (Lead Pastor of Living Word Church of the Nazarene), Fort Wayne, Indiana (Minister of Evangelism and Discipleship at Grace Point and Lake Avenue Churches of the Nazarene), and Kansas City, Missouri (Assistant Minister of Outreach and Evangelism at KC First Church of the Nazarene).
In January 2012, Scott, his wife, Jenni, and their two young daughters, Bekah and Sarah, became missionaries in the CIS Field (former Soviet Union). He was appointed strategy coordinator for the field in 2014.
As CIS field strategy coordinator, Rainey oversaw the work of the church in eight countries. He has helped bring unity to field leadership and implemented a vision and strategy that saw five new churches in five different countries in 2016. In the past three years, the church has also been present in two new former Soviet countries, Belarus and Georgia.
Rainey is a graduate of Olivet Nazarene University, Nazarene Theological Seminary, and Houston Graduate School of Theology, where he earned a Doctor of Ministry degree with an emphasis in church dynamics.