One of the other consistent themes in the Old Testament is that kings fell into idol worship often times because they married women who worshipped idols. God warns the people repeatedly not to intermarry with unbelievers, but they do anyway. And inevitably, they fall into worshipping the same idols as their spouses.
One of the most ominous verses in the Old Testament for me is 1 Kings 11:2-3 — It says God clearly instructed his people not to marry unbelievers because marrying them would lead the people to worship other gods. Then the verse ends with this: “Yet [King] Solomon insisted on loving them anyway… And sure enough, they led his heart away from the Lord.” As a result, the kingdom was taken away from Solomon’s descendants, Israel fell into destruction, and eventually all of Israel was taken into captivity by a foreign nation.
My heart sinks every time I read these verses. What was true for Solomon is true for believers today. We have the same choice he had, and we will experience the same consequences he did/could have. We must refuse to partner with anyone who is an unbeliever or they will led our hearts away from the Lord. Everybody worships something, and we will inevitably worship the god(s) our spouse worships.
If we learn any lesson from the sobering stories of the Old Testament kings, it’s do not worship other gods. (Commandments 1 and 2) And the primary way to avoid doing this is to not marry those who worship other gods.
I recognize that this is easier said than done — the heart is a hard thing to control, and it is deceptive above all things. But then, of course, this must be hard. If it wasn’t, then all of these kings would not have made the same mistake. And this would not have been the first 2 of the Ten Commandments.