The president of the Irish Missionary Union, Father Tommy Murphy, has said "Ireland of the Welcomes" no longer exists.
Speaking at the "Festival of Mission", which ended in the RDS Dublin yesterday, he said "we are at a crucial stage in Irish history, which is either to include all cultures into society or to continue the segregation of different ethnic communities and therefore dismiss them to live on the social and economic fringes of Irish society".
Father Murphy continued: "Irish people, more than any other race, should recognise the need to create an environment of inclusion rather than exclusion, given the generations of Irish emigrants who have contributed both socially and economically to countries throughout the world.
"We as a nation need to recognise the advantages of welcoming people of various racial backgrounds who come to live, work and make their home here.
"It is time that Irish people accepted that Ireland is becoming a multicultural society. People are choosing to come to Ireland because of the life that it offers them, and we must give them the chance to build that life," he said.
"One of the lessons missionaries have learned, is that there is no need to be afraid of difference, it can benefit all of us", he said.
The festival took place over four days and highlighted the needs and experiences of migrants and minorities in Ireland, with contributions from the experience of Irish missionaries abroad.
The Irish Missionary Union (IMU) was established in 1970 to co-ordinate missionary efforts at home and abroad. It represents 73 Catholic missionary groups, religious and lay, which have personnel overseas.
At the moment there are almost 3,000 Irish Catholic missionaries working in 93 countries throughout Africa, Asia, Oceania, Latin America and the Caribbean.
The IMU provides training, research and networking for missionaries. It works in conjunction with the Irish Bishops' Commission for Missions as well as with the Government, APSO and Ireland Aid, on financial support for development and justice, and in the placement of volunteers.