Many Christians who come to Christ often discover that the friends they have acquired over time are no longer compatible with their new set of beliefs and standards. As born-again Christian, we have to put up with a lot at the workplace and out socialising. A holy standard of living does not want to hear sexual banter at the office, gossip, swearing, and anything else that grieves the Holy Spirit. So, we can answer the question in many ways. To date someone who is not saved is a definite no, it’s unbiblical and wrong because you are unequally yoked:
2 Corinthians 6:14
“Do not be unequally yoked with unbelievers. For what partnership has righteousness with lawlessness? Or what fellowship has light with darkness?”
A born-again Christian can fall in love with an unbeliever, but it should never become a mission to save that person’s soul, just so you can be with them. This is the flesh talking, and lust governing sound judgment. Friendship can of cause blossom and she could get saved, but her mind may be altered to look for another Godly person to date more compatible to her, who actually obeys the law. Don’t forget the believer has broken the law of 2 Corinthians 6:14. Jesus was more connected to the sinners than he was with anyone else.
As a believer made in the image of God, we are to attract unbelievers and try to sow a seed that might bear fruit. So, we can distance ourselves from ungodly people at work, because they are probably just that, work colleagues. Any unsaved friends that are closer to us might respect more the Christian faith, are of cause open to hearing from time to time the gospel, and might ask questions.
There is a line though that even a born-again believer must decide. We are to preach against sin in love. Some homosexual friends I have befriended in the past had to be cut off from my life because I found I had nothing in common with that person. I could see darkness in their face, and the sexual perverse banter was not what I now wanted to hear.
Lifestyles can play a huge part in the character of a believer, to the point society thinks we are boring and not normal because we find joy elsewhere than drink, drugs and nightclubs.
A true Christian must evangelise, but if that person is not, or will not turn to the truth, then we (must) turn them away. Never participate in their sin, or places that attract bad spirits.
If they get tired of you, then they have rejected the Lord:
1 Corinthians 15:33
“Do not be misled: “Bad company corrupts good character.”
The question is are you influencing them, or are they influencing you?
So, can we have ungodly friends?
Absolutely yes, a Christian must evangelise. But we need to be careful we are not misled by bad company so we might end up sinning. The Lord’s Prayer teaches:
“Lead us not into temptation but deliver from evil.”
Never become more like the world, walk away if you have to.