“And I will have mercy on No Mercy, and I will say to Not My People, 'You are my people” (2:23). Hosea prophesied at the time when the Israel was split into two; Judah was the southern kingdom, and “Israel” was the northern. Israel had fallen deeply into idolatry, and Judah was heading the same way. Shockingly, God told Hosea to marry a prostitute to symbolize the situation: Judah was like an unfaithful bride, and God was the forgiving, merciful husband, calling His bride to come home.
The whole Bible is the story of God reaching out to rebellious humans, so that we can become what we were meant to be: "Children of the living God" (1:10).