Disclaimer: What I am about to share with you is not advice. I am not a counselor nor a psychologist. I am simply giving you "food for thought" based upon experience and Christian teaching. Hopefully, it will be helpful to you. It would be great to know if it is by your comments. I am sure that many Christians struggle with this.
Let's say, aside from the Christian verses non-Christian issue, that your relationship is progressing very nicely, and you both are considering sharing your life together. It can become a very serious matter to be dating someone who is not a Christian. Not only can it lead to many future problems, but the Bible warns against marriage between a believer and a non-believer. II Corinthians 6:14 very clearly states, "Do not be bound together with unbelievers; for what partnership have righteousness and lawlessness, or what fellowship has light with darkness?" Does this apply to marriage? Of course! Did you catch the words, "bound together?"
First and foremost, do NOT compromise your Christian beliefs just to avoid losing a potential life mate. At the first signs that the relationship might be getting serious, you need to openly discuss your religious persuasions. The sooner, the better! Obviously, the more emotionally attached you become, the more hurt will result if you have to end the relationship. Also, if the other person is involved in a religious group, secular organization, cult, or any type of questionable sect, about which you know very little or nothing, you must do your homework to find out how that particular group REALLY believes.
I have 2 suggestions to offer when discussing this subject. One, consider sharing your testimony as to how and why you became a Christian. Two, help the other person see that being a Christian is not about going to church as much as it is a relationship with God. Show them real, biblical Christianity. Too many people see only the church version. That is why they have tuned it out.
Another factor is to help the non-believing partner understand that there would be much difficulty in making a marrige work, on top of everything else that enters into this equation. You would need to talk specifically about things like church attendance, Bible study, prayer, family devotions, beliefs about the Bible, and the entire world view of the other person. Remember, there really is a night and day difference between a true, genuine, regenerated Christian and a non-believer in many areas of thinking.
Seek to understand the other person's position and background. Try to identify specific thinking and events that have happened in their life that are standing in the way of their becoming a Christian, and then prayerfully and patiently work with them in becoming receptive to the Gospel.
When you believe the timing may be right, ask them if they would like to invite Jesus into their life. If you do not know how to present God's plan of salvation, make an appointment with your pastor, then enjoy a happy life together!
If the other person is not coming around at all, to make a confession of faith, you then have a very tough decision to make, don't you?
If he or she does not want to accept Jesus and you decide not to marry, I still have encouraging news. You may have not only spared yourself from a lot of hurt and struggles, but also realize that their are others who can be the right person for you. I do not believe that there is only right person for you to marry, nor do I believe the Bible teaches that, contrary to what you may have heard from people at times.
There are many wonderful people with whom you can share your life. There are other articles I have posted on this topic. If you are getting married for the very first time, you may be helped by reading the article I posted entitled, "Before you Marry For the Very First Time Here are 20 Things You should Know."