Matthew Poole and continuators on Jeremiah 8:5

5 Why then is this people of Jerusalem slidden back, by a perpetual backsliding: They hold fast deceit, they refuse to return.

Either a universal backsliding. Or, rather obstinately resolved to hold on, though they see they are out of the way, not out of levity or inconsiderateness, the Heb. word signifies strength, the same used, Psal. 13.1. and translated for ever, implying a strong, stiff, stout refusal, see Isa. 57.17. chap. 5.3.

Either their injustice and couzenages in circumventing one another, which was so frequent among them, chap. 9.4, 5, 6. Mic. 7.3.4. or their hypocrisie whereby they think to deceive God, but they do indeed deceive themselves the great impediment of their Repentance, Isa. 44.20. or rather their sticking close to their false Prophets who did deceive them, thence incouraging themselves in their wickedness, and pleasing themselves, that their miseries should not come upon them. See on Isa. 30.10. chap. 5.31. and 14.13, 14. &c.