Jamieson, Fausset and Brown on Isaiah 45:15

15. God that hidest thyself--Horsley, after Jerome, explains this as the confession of Egypt, &c., that God is concealed in human form in the person of Jesus. Rather, connected with Is 45:9, 10, the prophet, contemplating the wonderful issue of the seemingly dark counsels of God, implies a censure on those who presume to question God's dealings (Is 55:8, 9; De 29:29). Faith still discerns, even under the veil, the covenant-keeping "God of Israel, the Saviour" (Is 8:17).