According to the Hebrew Bible:
* Judah (the Southern Kingdom): Was considered to have had a mixed record. Some kings were considered righteous and tried to follow God's laws, while others were seen as wicked and encouraged idolatry. Despite periods of unfaithfulness, it retained a connection to the Davidic line and the Temple in Jerusalem, which were central to the worship of Yahweh.
* Israel (the Northern Kingdom): Was consistently condemned for abandoning the worship of Yahweh and embracing idolatry from its very beginning under King Jeroboam. All of its kings are portrayed negatively in the Bible, and it was eventually destroyed by the Assyrians because of its unfaithfulness.
So, to summarize:
* Judah: Remained more faithful, but still had periods of unfaithfulness.
* Israel: Did not remain faithful.
It's important to note that this is a theological assessment from within the Hebrew Bible itself. Historical interpretations may differ.