Dr Morgan will warn Wales against the negative aspects of nationalism
Archbishop of Wales Barry Morgan is urging Wales to celebrate its identity, while warning against becoming "narrowly nationalistic".
Dr Morgan will make his call at Wales' leading cultural festival, the National Eisteddfod in Cardiff.
He will say Wales faces a challenge of keeping its identity and rejoicing in it without "excluding others".
Dr Morgan was leaving the Lambeth Conference gathering of Anglican leaders early to preach at the service.
He will say the eisteddfod is a time to celebrate Wales as a nation and the Welsh language.
But he will warn that any debate about race and nationality could lead to violence and hatred.
Wales, he said, had to learn to preserve its identity without allowing that process to become destructive.
He will outline how the gospel of Jesus warned against the danger of trying to establish an exclusive club.
Instead, it challenged people to reject the drive that can make individuals, families and nations exclude others.
"The particularities of culture, language and tradition are God's gifts to us for they define who and what we are," Dr Morgan will tell worshippers.
"But we also need to foster openness towards those who are different, the peoples and nations of our divided world."
Eisteddfod chief executive Elfed Roberts said: "We do appreciate the fact that Dr Morgan is leaving the Lambeth Conference early to preach at Wales' prime cultural festival."