(RNS) Holy Week is used by many Christians to reflect on the crucifixion of Jesus on Good Friday, and now more than 400 Catholic and evangelical leaders are using Jesus' state-sanctioned execution to call for an end to the death penalty.

“When they look at Christ on the cross, it’s a reminder of how very many millions of people have been executed by government in history and how grotesque it really is and, often, how unjust it is,” said David Gushee, an evangelical ethicist at Mercer University in Atlanta.

Gushee is one of the signers of the statement, as are two former presidents of the U.S. Conference of Catholic Bishops (Joseph A. Fiorenza of Galveston-Houston and William Skylstad of Spokane, Wash.); Miguel Diaz, former U.S. ambassador to the Holy See; and Jim Wallis, founder of the progressive Christian group Sojourners.

The letter urges governors, judges and prosecutors to end the death penalty, which the letter calls a "practice that diminishes our humanity and contributes to a culture of violence and retribution without restoration.”

Other signers include death penalty activist Sister Helen Prejean of "Dead Man Walking" fame; Lynne Hybels, wife of Willowcreek megachurch founder Bill Hybels; the Very Rev. Timothy P. Kesicki, head of all Jesuit priests in the U.S. and Canada; and Richard Cizik, a former vice president of the National Association of Evangelicals.

The letter follows a similar call by the National Latino Evangelical Coalition, which recently became the first national evangelical group to publicly call for an end to capital punishment, and Pope Francis, who called it "inadmissible, no matter how serious the crime committed."

As more groups are speaking about the issue, the letter also notes that it is “shameful” that the United States is one of the few developed nations that continues to execute convicts. According to Amnesty International’s 2014 report, about a third of the world has the death penalty but only nine nations regularly use it, including the United States, Iran, China, Sudan and North Korea.

Sister Simone Campbell of Network: A Catholic Social Justice Lobby, said that although she isn’t a leader in the death penalty movement, moral obligation requires speaking out against capital punishment.

“In a nation that values the dignity of all people, we must act out of that dignity as a society," she said. "And societies do not kill people. Period."

The letter also points to recent cases around the United States that the signers believe are unjust, including a case in Missouri in which a prisoner with brain damage was executed and a bill in Utah that revives the use of firing squads if lethal injection drugs are unavailable.

As a federal jury in Boston is poised to consider the death penalty for Dzhokhar Tsarnaev, should he be convicted in the 2013 Boston Marathon bombing, Gushee thinks life in prison without parole is a fair punishment. He said this allows for the possibility for release in cases of wrongful conviction -- a factor that has helped chip away at public confidence in the fairness of capital punishment.

To supporters of the death penalty, Gushee said he would "ask them to look at the arbitrariness of our death penalty system, the bias along the lines of race and class, the manifestly random way in which a small number of murderers are punished by death, and agree that the system is broken.”

KRE/MG END ADAMS