Counterfeit Gospel

Many Christians believe in it. It's even preached in many of our churches. It can be very convincing. It sounds like the real deal. But is it? In our culture, we need to be able to identify the differences between the fake gospel that many people have bought into and the real Gospel that alone can set you free both here on earth and into eternity. How do you differentiate between a counterfeit gospel and the genuine one?