She believed God would eventually work a miracle to cure a man who has been suffering from chronic kidney disease for more than 30 years.

But Dr. Ester Kwok, a Christian physician from Stanford Health Care in California, felt that such a miracle could only happen if she would help make it happen.

Feeling a calling from God, Kwok decided to donate one of her kidneys—even if this ran counter to the beliefs in her Asian country of origin—to help somebody who is not even her patient, who is in fact a total stranger. The man in dire need of a healthy kidney was Jonathan Chan, the son of one of Kwok's patients.

"I am a Christian, and I believe that God puts us in situations where he wants us to be his instruments," Kwok told The Gospel Herald as she recalled the momentous events that happened last year.

She said in the Asian country where she came from, donating an organ is a no-no. "One of the reasons Asians cannot donate is because we believe that our bodies are given from our mothers, and you have to honour your mother by honouring your body by keeping it whole and not doing any harm to it," she explained.

Despite this cultural constraint, she decided to donate a part of her body. "As Christians, we shouldn't just talk about helping others, but we also need to act," she said.

With Hebrews 10:38—"The just shall live by faith"—guiding her and with the support of her husband and four children, Kwok decided to join the National Kidney Registry.

Unfortunately, Kwok found out she was not a match for Chan. Still, she kept the faith that somehow she would still be able to help Chan by joining the national registry for chain donation, trusting that God could work a miracle that way.

Kwok's kidney went to another kidney patient whose originally intended donour was not an exact match. The same situation happened in Chan's case. He was able to eventually receive a new kidney from another donour—something that would be difficult to find if Kwok did not join the National Kidney Registry.

At first Chan refused to undergo surgery if that would entail Kwok losing one of her kidneys. Kwok had to reassure him that it was alright.

"I told him that mine was a free gift and he needed only accept just as eternal life was a free gift that I accepted, and since I was given eternal life, then how could I not give a small part of me when asked," she said.

"My motivation was this: Jesus died for me on the cross while I was yet a sinner, while I was yet a stranger," she added. "He gave me eternal life, and how can I not then reach out to somebody to give one organ to give them more time to believe in Christ, to give them time to find grace? I've been given so much—why not give a little back? I gave under anaesthesia, but Jesus gave without anaesthesia for all men. If he did this, how can I not do what God asked of me?"

Both Kwok and Chan underwent surgery in June 2015.

But that was not end of the story. When Kwok had her first check-up after donation, she met Chan and found out that his body appeared to be rejecting the donated kidney.

"I said, 'Lord, I went through all of this—I never pondered that rejection might be something that would happen. Did I go through all of this for nothing?'" she recalled.

Kwok said she heard the voice of God speak to her, gently reprimanding her for doubting Him: "I allowed this to happen," the voice said. "You must have faith, I wouldn't have done all of this for nothing."

A year later, Kwok saw Chan again—this time fit and healthy. His body has stopped rejecting the new transplanted kidney.

"Faith is believing everything is going to be okay," Kwok said.