52 If this witness of the voyagers seem inconclusive to you because they were Apostles,— though to me it comes with the greater weight for the same reason, though it surprises me the less—accept at any rate a corroboration given by the Gentiles. Hear how the soldier of the Roman cohort, one of the stern guard around the Cross, was humbled to the faith. The centurion sees the mighty workings of Christ's power; and this is the witness borne by him:— Truly this was the Son of God. The truth was forced upon him, after Christ had given up the ghost, by the torn veil of the Temple, and the earth that shook, and the rocks that were rent, and the sepulchres that were opened, and the dead that rose. And it was the confession of an unbeliever. The deeds that were done convinced him that Christ's nature was omnipotent; he names Him the Son of God, being assured of His true Divinity. So cogent was the proof, so strong the man's conviction, that the force of truth conquered his will, and even he who had nailed Christ to the Cross was driven to confess that He is the Lord of eternal glory, truly the Son of God.
Source: On the Trinity (New Advent)