Our God is a jealous God. This is seen here as God uses Jehu and others to destroy followers of Baal. Yet at the same time God is full of mercy as he does not destroy Jehu as he sinned as well by not obeying the Lord with all of his heart. Is not all sin equal in the eyes of the Lord? Then it is through grace alone that we are spared the full might of the Lord's wrath. I must remember this for many reasons, including because God has a plan, even for those that sin - we cannot question the value of others nor are we to judge.
2 Kings 10:28-33 (NIV)
So Jehu destroyed Baal worship in Israel. [29] However, he did not turn away from the sins of Jeroboam son of Nebat, which he had caused Israel to commit---the worship of the golden calves at Bethel and Dan. [30] The Lord said to Jehu, "Because you have done well in accomplishing what is right in my eyes and have done to the house of Ahab all I had in mind to do, your descendants will sit on the throne of Israel to the fourth generation." [31] Yet Jehu was not careful to keep the law of the Lord, the God of Israel, with all his heart. He did not turn away from the sins of Jeroboam, which he had caused Israel to commit. [32] In those days the Lord began to reduce the size of Israel. Hazael overpowered the Israelites throughout their territory [33] east of the Jordan in all the land of Gilead (the region of Gad, Reuben and Manasseh), from Aroer by the Arnon Gorge through Gilead to Bashan.