The NASB translates 1 Kings 22:21 as “then a spirit came forward and stood before the Lord and said, ‘I will entice him.’” But the Hebrew has the definite article with “spirit” (RUACH), and the mentioned in v 23 is explicitly the Spirit of Yahweh. Apparently, it’s THE Spirit that volunteers to be the lying spirit in the mouth of the prophets of Ahab. Ahab’s prophets are inspired, and are inspired by the Spirit of Yahweh, but the words they speak are misleading, equivocal, and intended to seduce.
The Spirit is, as Jim Jordan says, the divine matchmaker, the power of the Husband’s “seduction” of His bride. But here, the Spirit seduces in a different direction, to entice Ahab toward the grave.
