The Lord is merciful and doesn't punish Nineveh when they repent, but Jonah is unhappy about it. Some might think God is inconsistent, but Jonah knows God is merciful and will relent if people repent. Some believe God can change, but God is unchanging. God is passionate and fulfills his plans, so we should be encouraged that we are rooted in the unchanging true God, as James assures us.