Religious zeal may have a hidden agenda.
Religious zeal can go too far.
Let's approve the programs of unbelievers when they are in line with the word of God. It is noted that Jehu had religious zeal, which can be good. Jehu removed any possible claims to the throne by remnants of Ahab's line. He forced the hands of the officials and elders in Israel, and had them kill all seventy sons of Ahab, and then he killed the forty-two brothers or relatives of King Ahaziah of Judah. He had already killed King Ahaziah of Judah and King Jehoram of Israel.