Gary is a Methodist minister and directs a conflict transformation organization based in Belfast called "Rethinking Conflict." Prior to this he spent 27 years as a Methodist clergy person in parish ministry in Belfast and has played an integral role in the Northern Irish peace process. He played a key role in establishing the Skainos project, which is a world class urban centre developed in a post conflict society as a model of co-existence and shared space, and it is acknowledged as the largest faith-based redevelopment project in Western Europe. Mason is a close advisor to Protestant ex-combatants on the civilianisation efforts of paramilitaries. He was instrumental in facilitating negotiations with paramilitaries and government officials, and in 2007 his contribution was formally recognized by the Queen. In 2009, Mason’s church was the stage from which Loyalist paramilitaries announced their weapons decommissioning. Mason has lectured in political and academic forums throughout Europe, South Africa, the Middle East and the U.S.A. on lessons from the Irish peace process.
He holds a PhD in Psychology from the University of Ulster, completed his theological studies at Queens University, and a Bachelor’s in Business Studies from the University of Ulster. Gary is a Research Fellow at the Kennedy Institute for Conflict Intervention at Maynooth University in Ireland. He is an Adjunct Professor at the Candler School of theology at Emory University in Atlanta lecturing on reconciliation peace building, the history of the N Ireland conflict, racism, sectarianism and conflict transformation.