2 Kings 23:28-32 — Now the rest of the acts of Josiah, and all that he did, are they not written in the book of the Chronicles of the kings of Judah? In his days Pharaoh–nechoh king of Egypt went up against the king of Assyria to the river Euphrates: and king Josiah went against him; and he slew him at Megiddo, when he had seen him. And his servants carried him in a chariot dead from Megiddo, and brought him to Jerusalem, and buried him in his own sepulchre. And the people of the land took Jehoahaz the son of Josiah, and anointed him, and made him king in his father’s stead. Jehoahaz was twenty and three years old when he began to reign; and he reigned three months in Jerusalem. And his mother’s name was Hamutal, the daughter of Jeremiah of Libnah. And he did that which was evil in the sight of the Lord, according to all that his fathers had done.

Josiah led a great revival. He drove the worship of false Gods out of Judah, destroyed the idols, put the false prophets to death. As soon as he died, his son came along and reversed his work. “Oh yes”, we say, “that’s one of those familiar sin/repentance cycles in Israel”. But it’s not that simple. If I look at my own life I can see a similar cycle.
I sin. Something happens to draw my attention to my sin. I repent. I forget. The cycle happens again. It’s an old, old, process. King Solomon knew all about it – “As a dog returneth to his vomit, so a fool returneth to his folly.” (Proverbs 26:11).
So what’s the cause? Am I a willful child, choosing the wrong path time and again, for my own pleasure? Well yes, I am – but there’s more to it than that. There’s a reason for it … In fact, I have a nasty disease that I share with you, and we both share with everyone we meet. Definition. Ever since Adam sinned, every person ever born has been born into a sinful state that is the root of all the actual sins they commit. That corruption of our nature is called “original sin”. The good news is there is a cure! In fact you might say I’m in remission.
So what’s the cure? Paul lays it out in his letter to the Romans. The key part for answering this question is in chapter 5:

Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned: …
… For if by one man’s offense death reigned by one; much more they which receive abundance of grace and of the gift of righteousness shall reign in life by one, Jesus Christ. (Romans 5:12, 17)

Adam brought the sickness. Jesus brings the cure. When I took Jesus as my Savior, He started driving sin out of me. It’s a long job. I still sin. It’s a stubborn infection … but thank God, I will be well.