John Calvin Reformed @genevareformer

2. He was in the beginning. In order to impress more deeply on our minds what had been already said, the Evangelist condenses the two preceding clauses into a brief summary, that the Speech always was, and that he was with God; so that it may be understood that the beginning was before all time.

Matthew Henry Presbyterian @wholebiblehenry

Austin says (de Civitate Dei, lib. 10, cap. 29) that his friend Simplicius told him he had heard a Platonic philosopher say that these first verses of St. John's gospel were worthy to be written in letters of gold. The learned Francis Junius, in the account he gives of his own life, tells how he was in his youth infected with loose notions in religion...

Commenting on John 1:1-5

John Gill Reformed Baptist @doctorgill

The same was in the beginning with God. This is a repetition of what is before said, and is made to show the importance of the truths before delivered; namely, the eternity of Christ, his distinct personality, and proper deity; and that the phrase, in the beginning, is to be joined to each of the above sentences; and so proves, not only his eternal existence...