John Calvin Commentary Luke 2:13

"And suddenly there was with the angel a multitude of the heavenly host praising God, and saying," — Luke 2:13 (ASV)

And suddenly there was present with the angel a multitude. An exhibition of divine splendor had already been made in the person of a single angel. But God determined to adorn his own Son in a still more illustrious manner. This was done to confirm our faith as truly as that of the shepherds.

Among men, the testimony of “two or three witnesses” (Matthew 18:16) is sufficient to remove all doubt. But here is a heavenly host, with one consent and one voice bearing testimony to the Son of God.

What then would be our obstinacy, if we refused to join with the choir of angels in singing the praises of our salvation, which is in Christ? Hence we infer how abominable in the sight of God unbelief must be, which disturbs this delightful harmony between heaven and earth. Again, we are convicted of more than brutal stupidity if our faith and our zeal to praise God are not inflamed by the song which the angels, in order to supply us with the matter of our praise, sang in full harmony.

Furthermore, by this example of heavenly melody, the Lord intended to recommend to us the unity of faith and to exhort us to join with one consent in singing his praises on earth.