Isaiah 48:2

2.For from the holy city they are called. He continues the same subject, and by different words exposes their false boasting; for they falsely boasted that they were the citizens of “the holy city,” which they defiled by their vices and crimes. Jerusalem ought to have been “holy,” for God had consecrated her to himself; but she had prostrated herself to iniquities, so great and so numerous, that she scarcely retained any holiness. We see in Psalms 15:2, what the true citizens of Jerusalem ought to be; but because the Jews were not ashamed of mocking God, they reckoned it enough to be protected by the shadow of the Temple.

And rely on the God of Israel. When he says that they “rely on Jehovah,” he does not speak of sincere belief, but of empty confidence; for, as good men rely on God, and trust him with their whole heart, so hypocrites falsely make pretensions to his name, and are intoxicated by unfounded belief, and fearlessly despise everything, and even boast confidently of these words, “God will assist us, he will not cast off his people;” as if God wished to encourage their wickedness. In a word, by trampling him under their feet, they loudly declare that they rely on themselves for safety; but, lest they should think that they will not be punished for this mockery, the Prophet assures them that God loses nothing of his authority, when he is thus misrepresented by hypocrites; for, when he calls him Jehovah of hosts, he adds this by way of threatening, that they might know that God, under whose name they falsely sheltered themselves, was strong enough to punish them, and at length would not permit them to make him the subject of mockery.