2 Kings 17:30-33 The men from Babylon made Succoth Benoth, the men from Cuthah made Nergal, and the men from Hamath made Ashima; the Avvites made Nibhaz and Tartak, and the Sepharvites burned their children in the fire as sacrifices to Adrammelech and Anammelech, the gods of Sepharvaim. They worshiped the LORD, but they also appointed all sorts of their own people to officiate for them as priests in the shrines at the high places. They worshiped the LORD, but they also served their own gods in accordance with the customs of the nations from which they had been brought. 2 Kings 17:39-41 Rather, worship the LORD your God; it is he who will deliver you from the hand of all your enemies. They would not listen, however, but persisted in their former practices. Even while these people were worshiping the LORD, they were serving their idols. To this day their children and grandchildren continue to do as their fathers did.
Syncretism is the fusion of different forms of practice or belief. Syncretism is not a sin when biblical truth and moral standards are not involved. The fact that Mexican culture and American culture are so intertwined that tacos are just as American as Mexican is syncretism, but it is not sinful syncretism. The fact that baseball is just as much Japanese as American and the martial arts are now as American as Asian is syncretism, but it is not sinful syncretism. However, when vestiges of pagan religions and unbiblical beliefs and practices are mixed in and fused with the gospel of Jesus Christ, it is not only syncretism—it is sinful syncretism. Sinful syncretism is subtle. It doesn't happen overnight. Changes usually occur slowly and insidiously. Little by little the culture drifts away from God and His standards. This is exactly what happened in the 8th century B.C. when the northern kingdom of Israel was conquered by the Assyrians. The sinful syncretism that resulted is a lesson from history for growing Christians today.