William Burkitt on John 20:28

These words may be considered two ways.

1. As an abrupt speech, importing a vehement admiration of Christ's mercy towards him, and of his own stupidity and dullness to believe.

Learn hence, that the convincing condescension of Christ turns unbelief into a rapture of holy admiration and humble adoration.

2. This expression of Thomas, My Lord and my God, contain a short, but absolute, confession of faith. Thomas rightly collects from this resurrection, that he was Lord, God blessed for evermore, the true Messias, the expected Redeemer, and accordingly with an explicit faith he now professes his interest in him, saying, My Lord and my God.

Yet note, that this resurrection could not make him God, and render him then the object of divine worship, if he had been only a creature before.

And farther observe, that Christ doth not reprove Thomas for owning him as God, which shows that Thomas did not mistake in owning the divinity of Christ.