The political cause of the captivity was the repeated revolt of Judah against the power of Babylon. Relying on the help of Egypt, the king broke his promise of fidelity and refused to pay the tribute he had promised to pay. The prophets uttered many warnings against this suicidal course, and still more against the idolatry and accompanying immorality which prevailed. They assured the nation that, beset as Judah was by dangers from her powerful neighbors, she would be safe, if only she would be faithful to God. But the king and people were continually forsaking him and turning to evil courses, until at last God gave them up to their enemies. This was the spiritual cause of the captivity. The neglect of the Sabbatic years, mentioned II Chronicles 36:21, was only one of many provocations. The writer mentions it incidentally, to show that what the people would not do voluntarily, was done when they were carried away and the land rested seventy years.