'Unfaithful' in the Bible

Because he had been unfaithful to the LORD, during the fifth year of King Rehoboam's reign, King Shishak of Egypt attacked Jerusalem

But after he had become strong, in his arrogance he acted corruptly and became unfaithful to the LORD his God, and he dared to enter the LORD's Temple to burn incense on the incense altar.

and they opposed King Uzziah. "Uzziah, it's not for you to burn incense to the LORD," they told him, "but for the priests to do, Aaron's descendants who are consecrated to burn incense. Leave the sanctuary now, because you have been unfaithful and won't receive any honor from the LORD God."

because the LORD was humiliating Judah because of King Ahaz of Israel, since Ahaz had brought about a lack of restraint within Judah and had remained unfaithful to the LORD.

In the midst of his troubles, King Ahaz became more and more unfaithful to the LORD.

"Pay attention to me, you descendants of Levi! Consecrate yourselves and the Temple of the LORD God of your ancestors by taking out from the Holy Place whatever is unclean. Our ancestors have been unfaithful. They practiced what the LORD considers to be evil, abandoned him, turned their faces away from the place where the LORD resides, and turned their backs to him.

In addition, we have prepared and rededicated all of the utensils that King Ahaz threw away during his unfaithful reign, and now they're back in service at the LORD's altar."

Meanwhile, all the officials who supervised the priests and the people remained unfaithful, following the detestable example of the surrounding nations. They polluted the LORD's Temple that he had consecrated in Jerusalem.