As a friend, the first thing to do is pray for her.  In Philippians 4:6, we are told to pray about everything.  This is one of those situations where you need to allow the Lord to speak to you and guide you.  Consider when you were in her situation and reflect upon how you would have received a friend’s rebuke. 

When you approach your friend, do it out of love not condemnation (leave that for the Holy Spirit).  1 Corinthians 13 is not limited to marriages, but applies to all of us: 

Love is patient and kind.  Love is not jealous or boastful or proud or rude.  Love does not demand its own way.

The Lord and His Word do not need our help to transform lives.  Sometimes we need to get out of the way for God to work.  Be careful to not force your thoughts, beliefs and opinions on her or wave verses in her face to make her change.  Share your own experience and what God has taught you—but do it with love.

But the way of the wicked is like complete darkness.  Those who follow it have no idea what they are stumbling over (Proverbs 4:19).

Oftentimes when we are in a relationship, we lose focus on the things that are most important in our lives; we don’t even realize the relationship is leading us astray.

SHE SAID:  When I first read your question, the first image that popped into my mind was Robot from Lost in Space.  Remember that campy, ‘60s sci-fi television show? 

As a young child in the ‘70s, I remember watching the reruns of it on the weekends, as the Robinson family (yes, it was a space-age version of Swiss Family Robinson) was stuck in space and trying to figure out how to get back to Planet Earth.

Precocious, youngest son Will Robinson was always getting into some sort of mischief in the space ship or on the random planet that the family had landed on, while drifting out in the cosmos.  When Will was about to do something foolish, Robot (with flailing “arms”) was always nearby to warn:  “Danger, Will Robinson!  DANGER!!!”

And so to you, dear reader, I offer the same advice for your friend today:  “DANGER!”

Dabbling in dating relationships with non-Christians is like playing with fire.  It is not harmless, and you will get burned (whether you feel it or not).  I speak from personal experience, and I also speak as a friend who has seen other friends slide quite easily down this slippery slope. 

Even if you choose to skip over the entire book of 2 Corinthians in your Bible, no one can deny that chapter 6, verses 14-16, is ultra clear on this subject matter:

Do not be yoked together with unbelievers.  For what do righteousness and wickedness have in common?  Or what fellowship can light have with darkness?  What harmony is there between Christ and Belial?  What does a believer have in common with an unbeliever?  What agreement is there between the temple of God and idols?  For we are the temple of the living God.  As God has said:  “I will live with them and walk among them, and I will be their God, and they will be my people. 

So, in essence, don’t even go there.  Don’t even strike a match.  Step away from the matchbox.  “Danger, fellow Christian!  DANGER!” 

Sure, we all understand this and know that God has set up these unequally-yoked perimeters to protect his children.  But that doesn’t mean that it is easy for us to follow these instructions (2 Corinthians 10:5).