Mark was born on June 1, 1959 in Rome, New York where his father was stationed with the U.S. Air Force.  He was the second of four siblings; one older brother and two younger sisters.  The Tews family was stationed at various military bases around the United States as well as a three-year assignment in Germany.  In 1977, Mark graduated from Concordia Lutheran High School in Portland, Oregon.  He was enrolled at Concordia Lutheran College in Portland, but when his father retired from the Air Force, the entire family moved to Miami, Florida.  In 1982, Mark graduated from Concordia Lutheran College in Austin, Texas with a B.A. degree.

In June 1983, Mark was married to Kathleen “Kathy” Sue Reinhardt of Houston, Texas.  Kathy was also a 1982 graduate of Concordia Lutheran College in Austin, Texas.  Kathy was a teacher at numerous Lutheran elementary schools in Texas, Missouri, and Virginia during their marriage.  They have two sons, Alex and Zachary.  Alex and his wife, Katie, are both U.S. Marine Corps veterans and have three daughters; Grace, Madison, and Averie.  They reside in Alvin, Texas where they are both teachers.  Zachary and his wife, Dana, reside in Springdale, Pennsylvania where they are both teachers.

In June 1992, Mark graduated from Concordia Lutheran Seminary in St. Louis, Missouri with a Master of Divinity degree.  In July 1992, Mark was ordained at Saint John's Lutheran Church in Dumas, Texas.  In June 1996, Mark was commissioned as a U.S. Navy Reserve Lieutenant Junior Grade (O-2) and reported to Navy Chaplain School in Newport, Rhode Island in July 1996.  He then faithfully served as a U.S. Navy Chaplain for twenty years before retiring.  In July 2016, Mark accepted the call to serve as Pastor of Trinity Lutheran Church in Uvalde, Texas.  Mark and Kathy moved to Uvalde in August 2016 and he was installed as Pastor of Trinity Lutheran Church on September 4, 2016, where he continues to serve.