For a born-again Christian, marrying a nonbeliever is sin. Before salvation, we were God’s enemies (Romans 5:10); after, we are His children (Romans 8:14-16). We should not unite with His enemies, as it can lead us away from Jesus.
2 Corinthians 6:14-18: “Do not be unequally yoked with unbelievers. For what fellowship has righteousness with lawlessness? You are the temple of the living God.” Marriage is the closest human union.
Not marrying nonbelievers isn’t unloving; we are called to love everyone, even enemies (Matthew 5:43-46, 22:39).
Salvation isn’t based on efforts but on being sealed with the Spirit (Ephesians 1:13-14) and kept by God (1 Peter 1:2-5). Ensure true salvation, as superficial belief is possible (Matthew 13:1-23). God’s Spirit gives desires to please Him (Philippians 2:13).
Related articles:
Got Questions: Marrying an Unbeliever
Grace Gems: A Call to Separation