Hosea's life is an object lesson showing the unfaithfulness of the Northern Tribe of Israel. He was to marry a harlot, and they had three children. The first was named Jezreel as a reminder of the sin of Jehu in the town of Jezreel (2 Kings 10:11). The second was a girl, and her name was Lo-ruhamah which meant she did not receive mercy, and then another boy named, Lo-ammi which meant not my people. The Lord's people had sinned to the point that the mercy was done and they would no longer be the people of the Lord. After the children, Gomer left and went back into harlotry, and the Lord commanded Hosea to go again and buy her back as his wife. There are various themes throughout this book: God's people had no knowledge of Him, the religious leaders led the people astray, there was great immorality in the land, the Lord will bring judgment, there is a cry to turn to the Lord, and then there will be a day when the Lord will bless Israel again, and they will once again receive mercy and they will once again be God's people.
