(CNN) Hillary Clinton's longtime pastor plagiarized the writings of another minister in a new book scheduled to be released on Tuesday.

"Strong for a Moment Like This: The Daily Devotions of Hillary Rodham Clinton," is based on emails that the Rev. Bill Shillady, a United Methodist minister, wrote to Clinton from April 2015 through December of last year. Shillady described his emails as a way to minister to a candidate in perpetual motion.

The pastor and politician formed a spiritual bond after meeting in New York in 2002. Shillady co-officiated at Chelsea Clinton's wedding in 2010, presided over Clinton's mother's memorial service and blessed her grandchildren. Clinton is a lifelong Methodist.

Clinton appears on the cover of "Strong for a Moment Like This," and wrote a foreword for the book praising Shillady and his writings. She is scheduled to appear at an event next month in New York promoting the book. A spokesman for Clinton did not respond immediately to a request for comment.

Shillady holds the copyright on the book, which includes 11 pages of end notes crediting some source material. But it does not credit one source from which an especially emotional devotion borrowed heavily: a blog post by the Rev. Matthew Deuel, a pastor at Mission Point Community Church in Warsaw, Indiana.

In an interview with CNN last week, Shillady described rising at 4 a.m. on the morning after Clinton lost the presidential election to write the devotion. He did not mention borrowing material for it, which is listed first in his soon-to-be published book.

On Monday, Shillady apologized, saying he was "stunned" by the similarities between his email to Clinton and Deuel's column. In a text message, Deuel said he and Shillady talked on Monday, and that he had accepted Shillady's apology.

'Sunday is coming'

On November 9, the day after the election, Shillady sent Clinton an email titled, "Sunday is Coming." Last week, CNN published that email as part of an excerpt of the new book. The piece was widely shared on social media, with many liberals saying its sentiments struck an emotional chord.

On Saturday, though, Deuel contacted a CNN reporter, saying some paragraphs in Shillady's writings appeared to be "inspired" by a blog post he wrote in March 2016

For example, Deuel wrote: "For the disciples and Christ followers in the first century, Good Friday represented the day that everything fell apart. All was lost. The momentum and hope of a man, claiming to be the Son of God, the Messiah who was supposed to change everything, had been executed.

Shillady's email to Clinton, published in his book, says: "For the disciples and Christ's followers in the first century, Good Friday represented the day that everything fell apart. All was lost. The momentum and hope of a man claiming to be the Son of God, the Messiah who was supposed to change everything, had been executed."

Likewise, Deuel wrote: "Death will be shattered. Hope will be restored. Redemption is coming. But first, we must live through the darkness and seeming hopelessness of Friday."

Shillady's email to Clinton, published in his book, says: "Death will be shattered. Hope will be restored. But first, we must live through the darkness and seeming hopelessness of Friday."

Shillady echoes other ideas and phrases from Deuel's column as well, such as the notion that "life is filled with a lot of Fridays," times of trouble marked by jobs lost, friendships betrayed and bad medical diagnoses received.

When asked about the similarities between his email and Deuel's blog post, Shillady said the devotions he sent to Clinton were often pastiches of material he found on the Internet or old sermons he delivered as a former pastor. He had collected writings on Good Friday with the idea that it might be useful should Clinton lose the election, he said.

"I do not remember cutting and pasting from a particular column so much as bits and pieces from a variety of places on the Internet," Shillady told CNN on Monday.

In a later statement, Shillady apologized to Deuel.

"In preparing the devotional on the morning of November 9, I was determined to provide comfort with the familiar adage that 'It's Friday But Sunday is Coming.'" I searched for passages that offered perspective of this theme. I am now stunned to realize the similarity between Matt Deuel's blog sermon and my own. Clearly, portions of my devotional that day incorporate his exact words. I apologize to Matt for not giving him the credit he deserves."

Shillady said he did not know if other material from his forthcoming book, published by Abingdon Press, the book publishing arm of the United Methodist Publishing House, was likewise copied without attribution from other authors.

Mary Catherine Dean, Abingdon Press's editor in chief, said, "'Strong For A Moment Like This' is a heavily annotated work, in which Rev. Shillady has credited more than 200 sources. We worked with Rev. Shillady to faithfully cite all of the many contributors to the devotionals."

Dean said she has accepted Shillady's explanation that the lack of citation for Deuel's work was an oversight.

"His failure to attribute portions of the November 9 devotional does not change the fact that the 365 passages in the book were sent to Hillary Clinton, are part of the historical record of her campaign, and gave her the inspiration to stay strong."

'The last thing the world needs'

Deuel said he was "shocked" when he read Shillady's email to Clinton posted on CNN.com. But amid turmoil in the United States and elsewhere, the pastor said he is "not interested in publicly pursuing anything."

"The last thing the world needs right now is two pastors having a public dispute over a blog. The reality is, there's nothing new under the sun."

Indeed, many Christian ministers have used the phrase "It's Friday, but Sunday is coming," to contrast the sorrows of life with the despair and joy of the Christian apostles. Deuel said his column was inspired by a sermon by the Rev. S.M. Lockridge from the 1950s.

"If my blog then, in turn, inspired Rev. Shillady and it was used to encourage Hillary Clinton, then praise God for that! Could it have been done differently? Probably," Deuel said. "But for me to fire back publicly would be inappropriate and out of line on my part."