There is also a part that says "Preacher man, don't tell me, Heaven's under the earth." Mostly people would think that hell is under earth, not heaven. Preacher man is someone who preaches and tells people wise words and stories. If someone who is wise tells you that heaven is under earth, you would believe it. But in reality, hell is under earth. In conclusion, the lyrics means that wise people are tricking us to believe in them.