In a Dec. 5 statement, Bishops Richard Stika of Knoxville, Mark Spalding of Nashville, and Joseph Kurtz, apostolic administrator of Memphis, wrote that "the Church teaches that the death penalty is simply not necessary when society has other means to protect itself and provide a just punishment for those who break civil laws. Rather than serving as a path to justice, the death penalty contributes to the growing disrespect for human life."
"We believe that all those convicted of terrible crimes still retain their human dignity and deserve a chance to live," they added.
"To recognize the dignity of the lives of those on death row is not to deny the dignity of the lives of their victims or their grieving loved ones left behind. The lives of victims and sinners alike should be respected; the taking of another life will serve no purpose but vengeance."
Pope Francis is an outspoken opponent of the death penalty, revising in August the Catechism of the Catholic Church to classify its use as "inadmissible."
The pope's predecessor, Pope Benedict XVI, called leaders in 2011 to "make every effort to eliminate the death penalty."
Pope St. John Paul II prayed publicly for universal abolition of the death penalty.
In the 1995 apostolic exhortation Evengelium vitae, he wrote that governments "ought not go to the extreme of executing the offender except in cases of absolute necessity: in other words, when it would not be possible otherwise to defend society. Today however, as a result of steady improvements in the organization of the penal system, such cases are very rare, if not practically non-existent."
Haslam has declined to stop two other executions in 2018.
Miller's legal team has petitioned the U.S. Supreme Court for a stay of execution. He is scheduled to be executed at 7 p.m., Dec. 6.