2 Corinthians 6:14
Do not be unequally yoked together with unbelievers.

Do not team up, partner with, or bind yourself to an unbeliever.
I know this is a harsh statement these days.
Many would call it bigoted, racist, intolerant, or just plain mean.
Certainly, God is not saying to completely avoid unbelievers. You should show respect and friendship to unbelievers.
However, you should not go into a business partnership or a marriage with an unbeliever..
I guess if you are a carnal Christian it would not make much difference to you.
Perhaps it makes good business sense.
Maybe you’re in love and believe marriage will change your spouse.
I’ve discovered if a spouse won’t change for himself/herself, they are not going to change for you.
What you can do for an unbeliever is pray for them. Befriend them. Share Jesus with them.
And love them.