How do Christians decide what's right and wrong?  We don't have a long list of do's and don'ts, we live by the law of love.  In the 5th and 6th chapters of Galatians Paul explains that we are free from the legalism of the Mosaic law, but we live by 5 principles; Don't give in to legalism, Live by the Law of love, Follow the Holy Spirit, Do good to each other, and Don't boast in anything but the Cross of Christ.