This is what I call the 2 Corinthians 6:14 advice:
"Do not be yoked together with unbelievers..."
This verse exhorts that believers are not to marry or be associated with nonbelievers, for what partnership has righteousness with lawlessness? Or what fellowship has light with darkness? Some may say this is downright discriminatory. Others may ask how can we let go of this opportunity to evangelize and let them feel the love of God? It's amazing how disobedience can flourish in several guises for evangelism's sake, from evangeligaw to biblesteady.
Why is there such a need for spiritual compatibility?
1. A common treasure
It would be very difficult to share what is most precious to you to someone who does not deem it as equally important. One of my favorite hobbies is baking cakes. I love its sweet taste and soft & fluffy texture. I enjoy trying out new combinations and tasting the final product. But if the people at home don't have much of a sweet tooth nor have equal appreciation for this type of food then I have no one to share the joy with. Imagine the feeling of having no one to share it with. Wouldn't it a bit lonely? God would like to spare us the pain of having an unshared treasure when he says "Find a spouse whom you can share Me, whom you can share your greatest treasure.
2. A common blueprint
Building a house with different plans, different designs, different blueprints is just plain impossible. How can the carpenters use conflicting materials, follow varied dimensions and still build the same house? Same goes with relationships - if he has fixed his plans based on his background and life views, while she has her own set drawn from her life experiences. Thank God that He has planned to step into the picture, crumple all the faulty plans and provide His own blueprint for us to share. According to a reliable source, 90% of the conflicts we have in relationships have resulted from inflicting our individual blueprints, or simply disobying God's blueprint.
3. A common strength
It's inevitable to undergo series of life storms in this imperfect world. There's sickness, death, automobile accidents, bankrupcy, anger, depression, self-pity, hopelessness, boredom, peer pressure, heartache, natural disasters, broken homes. Many times people turn to pills, bottles and other abusive coping mechanisms. God however doesn't want you to end up with a person who's a weakling, who easily escapes and say "I want to be out of this relationship" or "I quit." What a difference it would make if both parties could turn to God and find refuge and strength in Him. The ability to tap into God's strength is a gift you can both share and enjoy.
4. Common values
There's an ungodly world out there that eats people up. The workplace, schools, media including the internet are bombarded with profanity and sexual innuendo, with immoral lifestyles and temptations. If you don't want your future children to be eaten alive for lunch, then make sure that you marry someone with the same values of yours, who knows the truth, the way and the life; or else your children might face a fork in the road: to follow mom who believes in Jesus or to follow dad who uses His name as a curse.
There's nothing better than being with someone who shares the same sensitivity to the will of God. Even if you both pray for the same matter individually / separately (i.e. changing lifestyle, giving away possessions, making a drastic move), the Spirit would lead you and your partner to a compatible conclusion. There's no reason to fight, much more to quit.
To the couples who are equally yoked, good for you!
To the couples who are unequally yoked, pray about it.
To those who are about to be equally yoked, cheers!
To those who are about to be unequally yoked, better think twice and make the right decision today.
(For more info, read Bill and Lynne Hybel's book entitled "Fit to be Tied")