Matthew 27:54

Truly this was the Son of God

(αληθως θεου υιος ην ουτος). There is no article with God or Son in the Greek so that it means "God's Son," either "the Son of God" or "a Son of God." There is no way to tell. Evidently the centurion (εκατονταρχος here, ruler of a hundred, Latin word kenturion in Mark 15:39) was deeply moved by the portents which he had witnessed. He had heard the several flings at Jesus for claiming to be the Son of God and may even have heard of his claim before the Sanhedrin and Pilate. How much he meant by his words we do not know, but probably he meant more than merely "a righteous man" (Luke 23:47). Petronius is the name given this centurion by tradition. If he was won now to trust in Christ, he came as a pagan and, like the robber who believed, was saved as Jesus hung upon the Cross. All who are ever saved in truth are saved because of the death of Jesus on the Cross. So the Cross began to do its work at once.