Tiffany Johnson from Concord in North Carolina revealed how "mountains moved" and she was able to get the medical care she needed.
Mrs Johnson was snorkling beside a boat off the coast of the Bahamas in May when the creature appeared and locked its mouth around her right arm.
She was quoted by Associated Press (AP) as saying: "I look back at my response, and the first thing I said was 'Help, help me Jesus!'
"That ministers to me; I cried tears about how the first thing that came out was him.
"Thank you, Jesus, that I relied on you when I had nothing else."
After wrestling with the animal, Mrs Johnson escaped the shark's grip but lost her hand and the lower section of her arm in the attack.
Mrs Johnson compared the stillness in her heart immediately after the incident to the peace that "surpasses all understanding", as described by Paul in Philippians 4:7.
Despite earlier concerns about locating their passports, managing their travel insurance provision and arrange emergency travel back to the United States, Mrs Johnson was flown to cosmestic surgeons in Charlotte for treatment.
Remembering the attack, she added: "When the Lord says a peace that surpasses all understanding, that was it; I was living that."
Mrs Johnson shared about her experience as a guest speaker a new New Life Church in Huntington, West Virginia last weekend.