So it is pretty important that we only serve one Lord and God and that God be the God of Israel. Joshua is in the sunset of his life and he wants to be sure that he leaves behind the nation in a healthy state and he can think of no other way to leave the nation in a healthy state than if they understand that they have to set up parameters to ensure that their progeny will only serve the Lord God.
This has been, and will continue to be, the one theme throughout all of Scripture, including when Jesus walks upon the earth. Love the Lord your God with all your heart, mind, soul, and strength. In an age of relativism where we often hear that it doesn’t matter what we worship or who we worship, as long as we are good people, this message of Scripture comes to us very directly and says: Well, no, actually it does matter. It matters quite a bit. But this message that Joshua gives: do not marry people who do not believe fundamentally the way that you believe, just might be seen as being narrow minded and not something we ought to pursue.
I am going to embrace this command in a way that might be somewhat contradictory. I would participate in a service where people of different religions are getting married. And by different religions I don’t mean a Baptist and a Presbyterian. We are the same religion, we are Christians. But I mean a Jew and a Christian, or a Muslim and a Christian, I would take part in this service. But, I would take part only if I could proclaim the good news of the Gospel in that service.