(RNS) — Philip Yancey, a beloved evangelical author and speaker, will retire from public ministry after admitting to a long-term affair.

“My conduct defied everything that I believe about marriage,” Yancey, 76, wrote in a letter to Christianity Today. “It was also totally inconsistent with my faith and my writings and caused deep pain for her husband and both of our families.”

Christianity Today, where Yancey had been a columnist and contributor for decades, reported the news of his retirement.

Known for his thoughtful and poignant books on faith, with titles like “What’s So Amazing About Grace,” “Disappointment with God,” and “Where is God When it Hurts,” Yancey’s writing connected with millions of evangelical readers, helping them wrestle with doubts about their faith and the hardships of life.

His books sold a reported 15 million copies and Yancey remained a popular speaker at churches and Christian events, even after being diagnosed with Parkinson’s in 2023.

He had been scheduled on Wednesday to speak at Lake Avenue Church in Pasadena, California, at a service commemorating the wildfires that struck that community, before news of his retirement broke.

In his letter to CT, Yancey, who has been married for 55 years, said he has withdrawn from all writing, speaking and social media and entered a counseling program to deal with the damage caused from what he called an 8-year-long affair with a married woman.

“Instead, I need to spend my remaining years living up to the words I have already written. I pray for God’s grace and forgiveness — as well as yours — and for healing in the lives of those I’ve wounded,” he wrote in his letter to CT.

In a statement, Yancey’s wife, Janet, asked for prayer, saying she knows God has forgiven her husband.  She also said she was dealing with the trauma of betrayal.

“God grant me the grace to forgive also, despite my unfathomable trauma. Please pray for us.”