Growing up, I always though that this verse was talking exclusively about marriage relationships. And while it would be wise for a young person to consider this carefully before choosing who to date, I believe that the application is greater. Let me give you an example:
After I got saved, I spent some time backsliding into my old life style. At one point, I decided to rent a trailer house with a couple of guys. One was a believer, and the other professed Christ, although he did not live much differently that the rest of us. At first things worked really well. As long as we were all doing the things that I was trying to escape, there was no conflict.
However, at this house over time, God began to work in me, to change my desires and I no longer felt that I could live the partying lifestyle that these guys desired. It really became difficult, because they want to invite people over to party, and I did not want to have that in my house. As the gap between our lifestyle increased, each day grated against my soul. I began to pray for a way out. However, it was some time before I could get out of the situation. I was so relieved, and I told God that I would never again live with an unbeliever.
When the apostle spoke about not being unequally yoked, the illustration he chose was taken from farming. A yoke was the harness that tied a team of oxen together. If a large strong oxen was harnessed to a small weak oxen, then the plow would be constantly pulled to the side. It would be nearly impossible to plow in a straight line. When you partner yourself to an unbeliever, they have different goals, desires, and standards than a Christian does. I had to learn that the hard way.
I am not saying that you cannot love an unbeliever. I still love my ex-roommates, and I pray that they will come to see the light. Jesus spent much of his time on earth with tax collectors, prostitutes, and sinners. But you would be wise to avoid committing to a relationship with an unbeliever, whether it is romantic, business, or even just as roommates. Light cannot have fellowship with darkness. Where light shines darkness ceases, and where darkness reigns light cannot be found.
