In this world, we are living and experiencing lots of challenges and of them sometimes comes from our own heart through love or marriage! My brother, my sister, though the best possible combination in a marriage is marrying a believer when you are one, the Bible still gives us a Word about "the rest" (verse 12), namely, those believers who marry unbelievers.
In this passage, Apostle Paul's 'command' firstly recall that the permanence of marriage is for all the married: "To the married I give this command (not I, but the Lord): A wife must not separate from her husband. 11 But if she does, she must remain unmarried or else be reconciled to her husband. And a husband must not divorce his wife" (1 Corinthians 7:10). Then, he affirmed the marriage commitment to the people in the Corinthian church who thought that they ought to divorce their pagan spouses and marry Christians to be able to serve Jesus. My friends, God's ideal is for a husband and his wife to stay together, even when one spouse is not a believer. Because He is loving and wants all to be saved, the Christian spouse is given all power to win the other to Christ... and if you search the Bible, you will see that this power is expressed through the character or love of the Christian spouse.
Now, we should also know that the blessings that flow to believers are also extended to others. Therefore, God regards such marriage as set apart too for His use by the presence of one Christian spouse. Of course, the spouse who does not believe in Christ does not receive salvation automatically but is blessed by this relationship. The same, the children of such a marriage have a godly influence and are set apart because of God's blessing on the family unit... until they are old enough to make their own decision for Christ.
Let's thank our loving Lord for His never-ending love that excludes nobody from His amazing grace. Stay blessed in Jesus' name.