What does Mark 15:39 mean?
Centurions rank much higher than common foot soldiers. This man is probably the senior officer at the crucifixion site, most likely the one responsible for supervising the event. Matthew adds that the centurion is also influenced by a sudden earthquake (Matthew 27:54) while Luke says the centurion "praised God, saying, 'Certainly this man was innocent!'" (Luke 23:47). Some translations in Mark say the centurion noticed how Jesus' last breath included the loud cry.Medical experts note that Jesus' cry at the end is not characteristic of someone who is dying of asphyxiation, which is the normal way crucifixion victims die. When the soldier later pierces Jesus' side with a spear, blood and water come out (John 19:34), indicating Jesus died from some form of hemothorax or a pleural effusion, both of which can be brought on by hypovolemic shock, or blood loss. The centurion knows Pilate believes Jesus to be innocent. He then witnesses the three hours of darkness (Mark 15:33) and the earthquake upon His death. If not at this moment then shortly after, he likely will have heard of the veil in the temple ripping from the top down, and the bodies of the Christ-followers who had died coming back to life (Matthew 27:51–53).
Scholars debate what the centurion means by calling Jesus "the Son of God." One possibility is that he can tell Jesus is accepting His fate as a servant of the deity He serves. Another is that he really does think Jesus is the Messiah, the Son of the Jewish God. In Roman culture, the emperor is considered the son of the gods, and the centurion may be saying Jesus is more divine than the emperor. Or, as a polytheistic Roman, he may believe Jesus is the literal son of one of the many gods. In whatever way the centurion means his statement, he echoes Pilate's inadvertent validation of Jesus' identity in the form of the sign on the cross. That Jesus is the King of the Jews and the Son of God is officially and spontaneously acknowledged by Gentiles, even if the meaning is not fully understood.