Amon's father, King Manasseh, had begun his reign at the age of 12. In his youthful, unrestrained activities, he rebuilt high places and altars that his father, Hezekiah, had broken down. Manasseh re-introduced forbidden practices to the people of Judah. He sacrificed his own children in the fires in the Valley of the Hinnom. He got involved with soothsaying, witchcraft, sorcery and spiritists. All of this surrounded Amon during his formative years, and no one, even a regretful Manasseh, steered him in any other direction. “Manasseh seduced Judah and the inhabitants of Jerusalem to do more evil than the nations whom the Lord had destroyed before the children of Israel.” (2 Chronicles 33:9)
Manasseh had reigned 55 years, and even though he had a change of heart in the latter years of his life, his influence and widespread idolatry was solidified among the population. His final acts as king evidently hadn't made an impression on Amon.
The words of the prophets of God are weighty. “Because Manasseh king of Judah has done these abominations, I am bringing such calamity upon Jerusalem and Judah. I will wipe Jerusalem as one wipes a dish, wiping it and turning it upside down. So I will forsake the remnant of My inheritance and deliver them into the hand of their enemies; and they shall become victims of plunder to all their enemies, because they have done evil in My sight, and have provoked Me to anger since the day their fathers came out of Egypt, even to this day.” (2 Kings 21:11-15)
Amon was ignorant and untrained, and no construction projects or military contributions mark his reign. The silence in God's Word regarding King Amon's life is deafening. The only positive thing about his life was his son, Josiah. Significantly, Amon is in the lineage that led to Jesus Christ. (Matthew 1:10)
But Amon had nothing to do with the true God, and never humbled himself before the Lord, as his father Manasseh had. Amon increasingly violated God's commandments. After two years as king, the servants of Amon conspired against him and assassinated him in his own house. But in retaliation, the people of the land executed all those who had conspired against King Amon. Therefore, Amon's son, eight-year-old Josiah, was made king. (2 Kings 21:19-26; 2 Chronicles 33:20-25)