The condensed account recorded here is also found in 2 Kings 8 & 9. Concerning the age of Ahaziah, the Kings’ account is more accurate; that Ahaziah was twenty two years of age when he assumed the reign of Judah.
Being mentored by his mother and grandparents, Athaliah along with Ahab and Jezebel, he took after their ways. Ahaziah joined forces with Jehoram in battle against Jehu, who killed all of his brothers including Ahaziah. When Athaliah, Ahaziah’s mother killed all the heirs to the throne with the exception of Joash; he was hidden by his aunt Jehoshabeath in the Holy of Holies until he was able to assume the reign of Judah.
Realize that the prophetic word concerning David’s house was contingent on one small, defenseless infant.
God preserved the Davidic line through this tenuous situation. God, as with David, will preserve and fulfill any prophetic word given to you or about you; even when there doesn’t seem to be much of a chance for it to come to pass.
He was faithful to His word to David and He’ll be faithful to the word give you as well. Dare to trust Him and His word to be fulfilled; for His faithful!
Just as He was faithful to bring Messiah, Jesus the Christ; so He will be for you.