The Duke of Edinburgh and the Queen's marriage was so strong because they were "so deeply rooted in Jesus Christ", Dr John Sentamu has said.
The former of archbishop of York said he and the duke had first discussed faith when Philip was deeply troubled about his children and their marriages.
Speaking to The Andrew Marr Show, Dr Sentamu said: "I think it was the ambassador's dinner at Buckingham Palace and he really was feeling very, very sorry for some of the things that were happening in his family - particularly his sons.
"He said, 'What would you say to me about the trouble that was happening with all my family?'
"I said, 'Well, your royal highness, you are a family like any other family, and every family goes through good times and bad times.
"'The important thing for me is that you should realise that if people are married they are not just a couple, there is a third and that's Jesus Christ, and they should begin to go to Jesus Christ'.
"He said, 'Of course, the Queen and I are so strong in Jesus Christ'."
Dr Sentamu said Philip had asked him to pray for his children and he had done so during the dinner.
He added: "There was this unbelievable depth of his rootedness, because (Philip) was so rooted in Christ, he didn't have any problem in relating to people about their faith or people who didn't believe at all.
"His faith was so strong, rooted in Christ, rooted in reality, rooted in his family, that actually he could be a free person.
"I have not met a couple that are so free - Her Majesty is exactly the same."
Dr Sentamu said he had prayed with the Queen and Philip, adding their prayers were never said aloud but "both of them would say amen".
He described it as "the most unbelievable experience".
The former archbishop said the royal family are proving they are no "different in grief to anybody else" by keeping to a small funeral for the duke.
"They want to be part of the grieving for the nation, for the many people who died from Covid-19 and for those who have not been able to be present when their loved one is being buried."
Dr Sentamu joked that Philip would have appreciated his shortened funeral service, because "the duke could not stand what he called 'long church'".