From 1964-1966, he attended the Windward Islands Bible Institute and Jamaica Bible College, Mandeville, Jamaica from 1966-1968. Following graduation from JBC, he did a pastoral internship at the Associated Gospel Assemblies in Portland Cottage, Clarendon, Jamaica for one year and in May 1969 returned to Grenada where he was ordained and installed as pastor of the St. John's Berean Bible Church, Gouyave, St. Johns, Grenada.

In 1972, he and his wife Elizabeth migrated to New York.  Pastor Griffith was called in 1987 by Calvary Baptist Church, New York City to be Pastor of Visitation and was ordained here on November 15, 1988. Since that time Winston has been given additional responsibility for membership classes and missions. 

Winston and Elizabeth are the parents of three young men, Kareem Andrew, Khalid Andre and Khadir Adrian.