Clinton, quoting Mormon leaders through the piece, argues in the article that Trump "lacks the morals to be our commander-in-chief," and in a nod to Mormons' history of religious persecution, knocks Trump's proposed Muslim ban.
"With a new, outrageous headline seeming to pop up every day, it's easy to forget that Trump showed us his true colors early on, when he proposed banning all Muslims from our shores," Clinton writes. "Trump's Muslim ban would undo centuries of American tradition and values. To this day, I wonder if he even understands the implications of his proposal."
The piece is Clinton's opening salvo in an attempt to undercut Trump in Utah, a state that is about 60% Mormon, according to some estimates. Some Mormon voters have grown concerned by Trump's candidacy, citing questions they have about his principles and comments he has made that hint at religious persecution.
Trump has fueled those concerns by going after Mitt Romney, the nation's most prominent Mormon politician and the 2012 Republican presidential nominee.
"Are you sure he's a Mormon?" Trump asked at a Utah event in March after Romney questioned the real estate magnate's candidacy.
Since its founding in 1830, Mormons have been persecuted and chased out of a number of areas they tried to settle. Members of the faith, after being expelled from Ohio, Illinois and Missouri, eventually settled in Utah in 1847.
Clinton nods to this history in her op-ed, noting that other Mormons have compared Trump's comments to "when Missouri Gov. Lilburn Boggs singled out Mormons in his infamous extermination order of 1838" and "President Rutherford B. Hayes' attempt to limit Mormon immigration to America in 1879."
Clinton also stresses her own commitment to religious freedom in the piece, noting her work as secretary of state to "protect the rights of religious minorities around the world -- from Coptic Christians in Egypt, to Buddhists in Tibet."
Clinton's chances of winning Utah are long, but Wednesday's outreach is more about forcing Trump to spend time and money to shore up support in a state that hasn't voted for a Democrat since Lyndon Johnson in 1964. While the campaign has hired Jefferson Campbell to run her campaign in the state and some polls show a close race, Clinton's aides acknowledge that winning Utah is highly unlikely.
But with Evan McMullin, a former House Republican aide and a Mormon born in Provo, Utah, announcing his plan to get on the ballot in Utah, Clinton could be helped in her effort to win the state.
McMullin's young campaign stresses that he is plugged into the Mormon church's power structure and in a close race in Utah, a strong McMullin showing could help put the state's six Electoral College votes into Clinton's column.