Isaiah 40:18 - Ellicott's Commentary On The Whole Bible

To whom then will ye liken God... — The thought of the infinity of God leads, as in St. Paul’s reasoning (Acts 17:24-29), to the great primary argument against the folly of idolatry. It is characteristic, partly of the two men individually, partly of the systems under which they lived, that while the tone of Isaiah is sarcastic and declamatory, that of St Paul is pitying, and as with indulgent allowance for the “times of ignorance.” We must remember, of course, that the Apostle speaks to those who had known nothing better than the worship of their fathers, the prophet to those who were tempted to fall into the worship of the heathen from a purer faith.