It's not wrong per se, but is highly not recommended. You could get by with "someone who doesn't really do the whole church thing" if they are at least Christian, but dating, especially marrying a non-Christian if you are Christian is not a good idea.
A christian, a true Christian, bases their entire life on following Jesus Christ. Every decision he or she makes usually involves prayer or consulting their faith. Problems can arise if they marry someone who does not do this. How will important decisions be made. If you feel God is calling you in one direction and the mate does not...what happens?
The Christian ideal of marriage is that two members of the body of Christ (the church) come together as one (emotionally, of course spiritually and even physically). The Christian ideal of marriage is basically two becoming one and having this recognized by God. Therefore they worship, grow and make decisions TOGETHER with their combined faith in Jesus Christ.