Your specific question asks whether it is wrong to chat or "online date" with someone who is not a member of our church. While it is not wrong to "chat" with people via the Internet, such contact with others—particularly people we do not know—is usually not advisable. While we might get advice from a Web site on a particular subject, striking up blind "relationships" online can be very risky and ill-advised. There are just some things we cannot know about people and their intentions when all we do is read written text from them.
As for dating someone outside of the United Church of God, you should seek and follow the advice and direction of your parents. Fundamentally, the Church teaches that people should marry in the faith, and as such, their dating (when they are old enough to do so) should ideally be with other people of like-mind, spiritually.
Often, young people will get interested in someone of the opposite sex who does not share their religious beliefs and will claim "we're just friends." Yet, that is usually the first step to a more serious relationship. As such, we feel that the admonition and principle explained by the apostle Paul in 2 Corinthians 6:14 applies to this situation: "Do not be unequally yoked together with unbelievers. For what fellowship has righteousness with lawlessness? And what communion has light with darkness?"
Of course, there is much more to the subject of dating that should be considered by a young person. If you'd like to read more about dating, an entire issue of Youth United focused on this important subject.