Well-known pastor, author, and theologian, Timothy Keller has announced that he has been diagnosed with pancreatic cancer.

Keller made the announcement Sunday afternoon on his Facebook page.

"Less than three weeks ago I didn't know I had cancer," says Keller. "Today I'm headed to the National Cancer Institute at the NIH for additional testing before beginning chemotherapy for pancreatic cancer next week back in New York City."

Keller is the founding pastor of Redeemer Presbyterian Church in New York City. He founded the church in 1989 alongside his wife, Kathy. 

He also is the President of Redeemer City to City, which starts new churches in New York and other global cities, and publishes books and resources for faith in an urban culture, according to his bio. In over 10 years they have helped to launch over 200 churches in 35 cities.

'Providential intervention'

Keller says that he was unaware that he was sick. "I feel great and have no symptoms," he writes.

"It was what doctors call an 'incidental pickup,' otherwise known as providential intervention. I have terrific human doctors, but most importantly I have the Great Physician himself caring for me. Though we have had times of shock and fear, God has been remarkably present with me through all the many tests, biopsies, and surgery of the past few weeks."

Keller has asked for prayers as he begins treatments, and specifically asks that God, "use medical means or his direct intervention to make the cancer regress to the point of vanishing."

He also asks for prayers for he and his wife, as well as the rest of his family.

"Running the race set before me with joy, because Jesus ran an infinitely harder race, with joy, for me. (Hebrews 12:1-2)," Keller says in closing.

Keller has written several books, many of which have been listed on the New York Times bestseller list. That includes The Reason for God and The Prodigal God, which have sold over 1 million copies and have been translated into over 15 languages.