After the kingdom had been pacified and its problems settled down, Jehoiada devoted himself to restore the religion of God, which had been destroyed by Joram and his successors. Therefore, in the first place, he persuaded the king and the entire people to renew the covenant made with God by their ancestors according to the words used in the traditional rite and to take an oath of reciprocal trust with one another. After that he turned to erase all the new cults and found that the people consented with him in an admirable manner. And so, after gathering a corps of soldiers, he immediately entered the sanctuary of Baal and destroyed its altars, smashed its statues and killed Mattan, the priest of that impious cult. Therefore, thanks to the authority of Jehoiada and his pious observation of the Law, the order of the sacred ministry, the sacrifices and the ceremonies were nearly brought back to the same honor that they had during the reign of David.
Source: ON THE SECOND BOOK OF KINGS 11:13