Jehoshaphat, king of Judah was wrong about Ahab. He thought Ahab’s repentance was genuine, but Ahab never believed in the LORD. According to 2 Chronicles 19:2, Ahab actually hated the LORD. Jehoshaphat’s marriage alliance with Ahab opened him up to spiritual attack and he was vulnerable because the wrath of God was upon him (2 Chronicles 19:2)
Jehoshaphat was a strong spiritual leader, so when he realized he had made a mistake, he set judges in the land to encourage godly behavior (2 Chronicles 19:6), and charged the priests to serve God faithfully (2 Chronicles 19:9). When the children of Moab, and the children of Ammon came against Jehoshaphat to battle, Jehoshaphat “set himself to seek the LORD, and proclaimed a fast throughout all Judah” (2 Chronicles 20:3).
When Jehoshaphat sought the LORD in prayer, he reminded God of a promise that was made to king Solomon:
If, when evil cometh upon us, as the sword, judgment, or pestilence, or famine, we stand before this house, and in thy presence, (for thy name is in this house,) and cry unto thee in our affliction, then thou wilt hear and help.
God’s response to Jehoshaphat’s prayer assured him that victory was possible, but a condition had to be met in order for their enemies to be conquered. The people had to put their trust in God.
And they rose early in the morning, and went forth into the wilderness of Tekoa: and as they went forth, Jehoshaphat stood and said, Hear me, O Judah and ye inhabitants of Jerusalem; Believe in the LORD your God, so shall you be established; believe his prophets, so shall ye prosper.
The Hebrew word translated believe in this verse, ’aman is the same word used in Genesis 15:6 where it says of Abraham “and he believed in the LORD; and he counted it to him for righteousness.” This verse refers to Abraham’s relationship with the LORD. It was the point in time when he “came to experience a personal relationship to God rather than an impersonal relationship with His promises” (539).
God delivered Jehoshaphat and his people from the children of Ammon and Moab when they began to sing and to praise him (2 Chronicles 20:22). Their heartfelt worship was a genuine sign that they were devoted to God. Jehoshaphat’s success as a spiritual leader resulted in a major military victory for Judah.