God tells Hosea to marry because “the land commits great whoredom by forsaking the LORD” Hosea 1:2. The marriage is tied directly to Israel’s unfaithfulness toward God in the text.
In Hosea 1:2–3 the story begins with a disturbing instruction: Yahweh tells Hosea to marry a “wife of prostitution” and to have “children of prostitution.” The reason given is that the land itself is behaving like a spouse who has been unfaithful, turning away from Yahweh. These verses function as the opening action of Hosea’s book and set the tone for what follows: the prophet’s family life becomes part of the message. The narrative starts with Yahweh speaking and giving a command, then quickly moves to Hosea’s compliance and the first birth.
Hosea opens with a divine command that is intentionally jarring: Yahweh tells the prophet to marry a “wife of prostitution” and to take “children of prostitution” (Hos 1:2). The text itself supplies the purpose: it is a public sign of Israel’s condition—“the land” is acting like an unfaithful spouse by turning away from Yahweh.
A careful answer keeps the immediate passage, the book's argument, and the whole-Bible storyline together, so the question is answered in context instead of as a detached idea.
Start with Hosea 1:2, then read the surrounding section so the answer stays connected to the passage's flow.
2When Yahweh spoke at the first by Hosea, Yahweh said to Hosea, Go, take to you a wife of prostitution and children of prostitution; for the land does commit great prostitution, [departing] from Yahweh.