What the Bible says about Marriage Outside Church
(From Forerunner Commentary)
Their children faced the same tests ours face today: a shortage of converted potential mates. Many of them had started dating and marrying "outside the church." Most of those they married never converted to God's truths but remained pagans. This led to whole families forsaking God's way of life. They forsook Israelite culture to the point that Nehemiah later writes that "half of their children spoke the language of Ashdod [a Philistine city], and could not speak the language of Judah" (Nehemiah 13:24). Boaz' marriage to Ruth, a foreigner of Moab, proves to be the exception, not the rule.