The predominately non-Christian Welsh community use the phrase as a joke. "Iaith y Nefoedd," they say, which translated means 'the language of heaven.'
Today it means 'everyone will speak Welsh in heaven.' It is one part celebrating the Welsh heritage and language, and one part remembering the nation's Christian history.
Nathan Ogle works for Greater Europe Mission in Caernarfon, a small Welsh port town with 10,000 residents. "There aren't many missions organisations reaching people through the Welsh language," he said.
Ogle said Wales used to be the cradle of Celtic missions. "There were several great Welsh revivals, the last one being in the early 1900s," Ogle said. "One hundred years ago you'd have the vast majority of Welsh people involved in a chapel or a church and they would be an on-fire Christian."
Now Ogle says less than one percent of the Welsh community are evangelical Christians. "So it almost seems, especially in the Welsh speaking community, that religion has forgotten them," he said.
The story Ogle is trying to tell in Wales is that God still cares about the Welsh people. He is in control and has not forgotten them.
"I believe that every person deserves to hear the Gospel in their heart language," Ogle said. "In the context of the Cymry Cymraeg, or the Welsh speakers in Wales, it shows investment and an authentic interest in them as people, not as a project."
Ogle has been working in Wales for five years. His team find strategic ways to engage with the Welsh community. Some of the things they do include hosting basketball camps, bringing artists and choirs to perform and engaging with people directly in friendships.
"Recently I got to see two people baptised," Ogle said. "One of those people was a direct result of our engagement in the community through a basketball camp."
His name is Cameron, and Ogle and his team met him through the camp when he was 14 or 15 years old. Ogle said when they came back the next year Cameron was interested in learning more about Christianity.
"You could see that God was talking to him," Ogle said. "Another year after that ... he decided that he did believe and he would follow Jesus."
Now Cameron is about to start a gap-year internship in Llanelli as a Christian worker where he'll also make a short trip to India on mission.
You can see Cameron's story in Welsh and English in the video below.
Ogle said he is increasingly trying to engage with people in a non-traditional way. "The religious tradition here leaves such a bad taste in people's mouths, and we try to work around that while still communicating the core truths of the Christian faith," Ogle said.
One of the ways Ogle is looking at accomplishing this is by setting up a local business that would engage people in the community and provide a platform for building relationships.
But in order to do this he needs people to come serve the Welsh community - people who want to help start bigger and better projects in the area.
He also said Wales needs prayer support for perseverance. "Nothing around here happens quickly," he said. "When you go into something you're starting at ground zero and sometimes you need to build, build and rebuild before you'll make any progress."
Ogle is praying for breakthrough, and small victories for the Gospel. "One day you might see a crack in the ice," he said.
Perhaps he is praying for breakthrough that one day 'iaith y nefoedd' will be true for Wales, and that everyone who speaks Welsh will be in heaven.