In addition to the point below, which is that the prohibition on murder does not extend to many instances of homicide the law seems justifiable, I believe you are also confused about the posture in which the question has come up.

The article discusses a member of the clergy who requested information about Alabama’s death penalty protocols to help her “pray on” the issue. The state pushed back, and “why does God need to know this information” was a snarky question asked of the clergy woman by the state’s lawyer. So the religious person and the entity executing people are on opposite sides of the issue. The state’s response could just as easily have come from an atheist.