John 6-69 son of the living God or Holy one of God?

John 6-69 And we believe and are sure that thou art that Christ, the Son of the living God. KJV

καὶ ἡμεῖς πεπιστεύκαμεν καὶ ἐγνώκαμεν ὅτι σὺ εἶ ὁ Χριστὸς ὁ υἱὸς τοῦ θεοῦ τοῦ ζῶντος

John 6-69 We have come to believe and to know that you are the Holy One of God.” NIV

καὶ ἡμεῖς πεπιστεύκαμεν καὶ ἐγνώκαμεν ὅτι σὺ εἶ ὁ ἅγιος τοῦ θεοῦ.

So which is the correct rendering of this verse?

The vast majority of manuscripts read as per the rendering of the KJV. This includes 17 Unials, Old latin, Syriac, Peshitta, Gothic, Armenian, Ethiopic Harclean an Palestinaian versions.

However P66 does not read the son of the living God but rather  “THE CHRIST, the HOLY ONE OF GOD” 

P75, Sinaiticus and Vaticanus all omit “the Christ” and simply state  “the holy one of God”. As per the reading of the NIV and most modern versions. 

Again the modern versions like so often choosing to follow Vaticanus and Sinaiticus. 

Agreeing with the KJV are many older english versions such as 

Wycliffe  Bible 1395

John 6-69 and we bileuen, and han knowun, that thou art Crist, the sone of God

Coverdale 1535
John 6-69 and we haue beleued & knowne, that thou art Christ the sonne of the lyuynge God. 

Bishops Bible 1568

John 6-69 And we beleue and are sure that thou art Christe, the sonne of ye lyuyng God

The Geneva Bible 1587
John 6-69 And we beleeue and knowe that thou art that Christ that Sonne of the liuing God.

This verse is actually quoted or referred to by many church fathers who use the rendering as it is found in the KJV. 

Irenaeus stated that Peter recognised Christ as the son of the living God. 

Irenaeus (130-202 A.D.)

“By whom also Peter, having been taught, recognized Christ as the Son of the living God.” (Against Heresies III: 11:6)

Athenasius also affirms that Peter called Jesus the Christ the son of the living God.

Why, Peter, who calls Christ a man capable of suffering, at once went on (Acts 3:15) to add, ‘He is Prince of Life,’ while in the Gospel he confesses, ‘THOU ART THE CHRIST, THE SON OF THE LIVING GOD.’ 

Letters of Athenasius Defence of Dionysius section 8 

Others who also referred to Peters statement as it is found in the KJV.

Cyril of Jerusalem 313-386 AD

And when they all became silent (for the matter was too high for man to learn), Peter, the foremost of the Apostles and chief herald of the Church, neither aided by cunning invention, nor persuaded by human reasoning, but enlightened in his mind from the Father, says to Him, THOU ART THE CHRIST, not only so, BUT THE SON OF THE LIVING GOD. And there follows a blessing upon his speech (for in truth it was above man), and as a seal upon what he had said, that it wasTHE FATHER who had revealed it to him. For THE SAVIOUR says, Blessed art thou, Simon Barjona, for flesh and blood hath not revealed it to thee, but MY FATHER which is in heaven . He therefore who acknowledges OUR LORD JESUS CHRIST THE SON OF GOD, partakes of this blessedness; 

John of Damascus 300-368

I ask, was it that the blessed Simon Bar-Jona confessed to Him, THOU ART THE CHRIST, THE SON OF THE LIVING GOD

Yet he speaks words which the tongue of man had never framed before:—THOU ART THE CHRIST, THE SON OF THE LIVING GOD. 

Peter is praised not merely for his tribute of adoration, but for his recognition of the mysterious truth; for confessing not CHRIST only, but CHRIST THE SON OF GOD. It would clearly have sufficed for a payment of reverence, had he said,THOU ART THE CHRIST, 

Next, the Father’s utterance, THIS IS MY SON, had revealed to Peter that he must confess THOU ART THE SON OF GOD, for in the words This is, God the Revealer points Him out, and the response, Thou art, is the believer’s welcome to the truth. 

John of Damascus – De Trinitate or On the Trinity. – De Trinitate or On the Trinity. – Book VI

Ambrose 337-397

Indeed, Peter’s single confession was abundant to warrant faith in Christ:“THOU ART THE CHRIST, THE SON OF THE LIVING GOD;”

337-397 A.D. Early Church Fathers – Nicene & Post-Nicene Fathers – Second Series – Volume 10 – Ambrose: Select Works and Letters – Dogmatic Treatises, Ethical Works, and Sermons. – Exposition of the Christian Faith. – Book IV. – Chapter V.

So we see there is plenty of evidence that the correct rendering is as is found in the KJV.