III. He shows them the vanity of all their hopes so long as they continued unreformed, v. 13, 14. Jerusalem is an inhabitant of the valley, guarded with mountains on all sides, which were their natural fortifications, making it difficult for an army to approach them. It is a rock of the plain, which made it difficult for an enemy to undermine them. These advantages of their situation they trusted to more than to the power and promise of God; and, thinking their city by these means to be impregnable, they set the judgments of God at defiance, saying, "Who shall come down against us? None of our neighbours dare make a descent upon us, or, if they do, who shall enter into our habitations?" They had some colour for this confidence; for it appears to have been the sense of all their neighbours that no enemy could force his way into Jerusalem, Lam. iv. 12. But those are least safe that are most secure. God soon shows the vanity of that challenge, Who shall come down against us? when he says (v. 13), Behold, I am against thee. They had indeed by the wickedness driven God out of their city when he would have tarried with them as a friend; but they could not by their bulwarks keep them out of their city when he came against them as an enemy. If God be for us, who can be against us? But, if he be against us, who can be for us, to stand us in any stead? Nay, he comes against them not as an enemy that may lawfully and with some hope of success be resisted, but as a judge that cannot be resisted; for he says (v. 14), I will punish you, by due course of law, according to the fruit of your doings, that is, according to the merit of them and the direct tendency of them. That shall be brought upon you which is the natural product of sin. Nay, he will not only come with the anger of an enemy and the justice of a judge, but with the force of a consuming fire, which has no compassion, as a judge sometimes has, nor spares any thing combustible that comes in its way. Jerusalem has become a forest, in which God will kindle a fire that shall consume all before it; for our God is himself a consuming fire; and who is able to stand in his sight when once he is angry?