This passage is often misinterpreted as a prohibition against all interracial or intercultural marriages, when it specifically addresses alliances with idolatrous nations that would erode Israel's faith; it is not about ethnicity or race but about avoiding spiritual contamination through close ties with those devoted to false gods, and misapplying it today ignores the New Testament's gospel of unity in Christ across all nations without such cultural barriers.
Joshua 23:12
King James Version (1769)
12 Else if ye do in any wise go back, and cleave unto the remnant of these nations, even these that remain among you, and shall make marriages with them, and go in unto them, and they to you:
Joshua warns the Israelites that turning back to ally with or intermarry the remaining Canaanite nations would lead to spiritual compromise, pulling them into idolatry and away from God's covenant blessings, emphasizing the need for complete separation from pagan influences to preserve their unique identity as God's holy people and inherit the promised land fully.