“Josiah was eight years old when he began to reign, and he reigned thirty and one years in Jerusalem. And his mother's name was Jedidah, the daughter of Adaiah of Boscath. And he did that which was right in the sight of the Lord, and walked in all the way of David his father, and turned not aside to the right hand or to the left.” 2 Kings 22:1-2 (See 2 Kings 22-23 and 2 Chronicles 34-35 for the complete history)
King Josiah reigned about 370 years after King David and was without a doubt the most powerful advocate for God since David. Josiah was actually prophesied to one day become king in 1 Kings 13:1-2 about 300 years before he was born. King David made sure that all the tribes of Israel worshiped the one and only true God. Solomon started allowing worship of other gods and then you have a long stream of kings either doing right in the site of God or doing wrong. The problem is that these kings from Solomon to Amon refused to dismantle all of the high places and worship centers of the false gods. Then in came King Josiah. He not only restored the temple, but destroyed all the worship sites of all the false gods in the kingdom of Judah. He even invaded the Assyrian held northern kingdom of Israel and destroyed the false god worship centers there. The Assyrians took the northern Kingdom of Israel in about 723 BC about 80 years before King Josiah’s reign in the southern Kingdom of Judah.
All this religious cleansing started after a priest named Hilkiah found the Book of the Law in the temple. Apparently, it was hidden there during the pagan occupation and worship within the temple. The priest kept it secret until Shaphan the scribe was sent by the King to get an inventory of the temple. After the scribe Shaphan read the Law he brought it to King Josiah. Shaphan read it to the king and Josiah tore his clothes in shame, because of how far the Hebrew people had fallen from what God intended. King Josiah in the 18th year of his reign gathered all the elders of Judah and read the newly discovered Pentateuch (Books of the Law) to them. He then commanded that the covenant with God be re-established and the elders agreed. That’s when all the reforms took place, and praise God that they did. He tore down the high places. He also burned human bones on the false god alters to defile them, which was prophesied 350 years before his reign in 1 Kings 13:2. He removed the groves where pagans worshiped, stopped the infant and child sacrifices and destroyed all the worship sites of the pagans. Then he reestablished Passover which had been abandoned some 500 years earlier after the last Judge, Samuel was replaced by the first King, Saul.
It is truly astonishing that Judaism survived to this day. The only explanation is the supernatural intervention of God. God also selected a people that would have a remnant that would never completely relinquish their love for God and His Law. God is amazing and knows exactly what he’s doing. The evidence is overwhelming. We can attribute our Christianity directly to God’s grace and mercy, Jesus’ willing sacrifice and the tenacity of His chosen people, Israel.