2 Kings 17:28
Then one of the priests whom they had carried away from Samaria came and dwelt in Beth-el, and taught them how they should fear the LORD. Then one of the priests whom they had carried away from Samaria came and dwelt in Beth-el, and taught them how they should fear the LORD.
The people concerned had once belonged to Israel but were divided from it for transgressing and neglecting God's statutes, and for this the Lord allowed an idolatrous nation to overcome them. After that conquest heathen colonists from Assyria settled among the Israelites left in Samaria and Galilee and intermarried with them, forming a mixed people. Their religion was gradually contaminated and corrupted by heathenism through this intermingling with idolaters.
When disaster convinced them that God was punishing their apostasy, they sought Jewish teachers to instruct them in the true religion. In answer to that request one of the priests carried away from Samaria was sent back to dwell at Bethel and teach them how they should fear the Lord and worship Him. Through this teaching their views of God and His requirements became clearer and their service came to resemble Jewish worship more closely.
Although they still reverenced the true God and claimed to worship Him, they represented Him by images of wood and stone before which they bowed. Those images were treated as reminders of the living God, yet they were still led to revere graven images, so they remained idolaters. Their worship according to the ceremonies given through Moses thus became a mixture of Judaism and heathenism mingled with the taint of idolatry that never wholly abandoned idolatry but still clung to it to a degree.
Their claim to be God's people while rejecting Jerusalem fostered lasting schism and enmity with the Jews. After the Jews refused them a share in rebuilding the temple at Jerusalem they built a rival temple on Mount Gerizim, where they worshiped according to the ceremonies given through Moses mingled with idolatry. They would not respect the temple at Jerusalem nor admit it was the true place of worship, leaving lack of harmony between them and the Jews. After their temple was destroyed by the enemy they seemed under a curse.