The oldest son of Robert Sr. and Victoria was born in San Antonio, Texas, and relocated to Los Angeles, California as an infant. He attended Los Angeles area schools and received his B. A. Degree from California State University at Dominguez Hills. He later received a honorary Doctorate in Ministry from Southern California School of Ministry 

He was saved at the Apostolic Faith Home Assembly at 6520 South Normandie Avenue, under the pastorate of the late Bishop Frank Bowdan. He was a member there for twenty-five years. He was called to the ministry in 1961. While a member of Apostolic Faith Home Assembly, he taught High School and College Sunday School class, and was a member of the Usher Board and Young Peoples' Choir. Pastor Thrash served as President of the International Youth Usher Board of the P.A.W.

As a member of the California/Nevada/Hawaii District Council of the P.A.W., Inc., he served as Young Peoples' Union Assistant Program Chairman. Pastor Thrash was ordained a licensed minister by the organization in 1979.

Pastor Thrash worked for the Los Angeles Area Council, Boy Scouts of America as an Associate District Executive from 1975 through 1977. He then worked for SAFECO Insurance Company as a commercial underwriter. After another short stint as a District Executive with the Boy Scouts, he began a six-year association with Pacific Telesis Company, serving in a variety of management positions. He left the phone company in 1985 to serve in the ministry full time.

In 1987, Dr. Thrash was part of the group of ministers that served in the inaugural group of Inglewood Police Department Chaplains. He served in this capacity for six years. He also served many years as an instructor at the Southern California School of Ministry and Bible Enrichment School of Theology.

Pastor Thrash is the husband of thirty four years to Elder Sandra G. Thrash, Executive Pastor of Christ-Centered A.R.M.E.D. Ministries. They are the parents of Bruce Bowen (Yardley) Tania and Nicole, son Rob IV, and  Shari (Cornelio). They are also the proud grandparents of Cornelio Busby II (CJ), Victoria Edwards, (Tori), Ojani and Ozmel Bowen.

As he enters his nineteenth year of pastoring A.R.M.E.D., Dr. Thrash continues to be a man of integrity who is leading God's people according to God's Word.