Speaking exclusively to People magazine, the friend, who wished to remain anonymous, said: "Meg is extremely faithful.
"We pray a lot together. We meditate. She has had, and especially has now, a very close relationship with God."
Meghan, 37, was baptised and confirmed in the Church of England at a private ceremony led by the Archbishop of Canterbury.
However, the American actress has remained rather private about her faith.
"A deep sense of gratitude and humility has guided her," the friend continued. "We can still be modern women and feel all the feels [sic] with feminism and be strong moms and strong wives but understand that [our] relationship [with God] is so critical."
Another close friend also called rumours that Meghan had insisted for St George's Chapel to be sprayed with air freshener ahead of her wedding, "outrageous".
The unnamed long-time friend added: "I can't think of anything more ridiculous.
"If people knew how spiritual she is and how serious and respectful she takes her relationship with God, she would never ask for something like that.
"The day after the wedding I said, 'You were so serene'. She has a huge loving fondness for Archbishop Welby. She's like, 'I'm there, I'm with Harry, I'm with you guys, and I'm with the leader of my church'.
"She doesn't think about the narrative: 'What will people think?' She doesn't do that. She really lives in the current moment. And when you do that, there's no fear."
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