2 Peter 2:1-3
1 But there were false prophets also among the people, even as there shall be false teachers among you, who privily shall bring in damnable heresies, even denying the Lord that bought them, and bring upon themselves swift destruction.
2 And many shall follow their pernicious ways; by reason of whom the way of truth shall be evil spoken of.
3 And through covetousness shall they with feigned words make merchandise of you: whose judgment now of a long time lingereth not, and their damnation slumbereth not.
Stay in that house, eating and drinking whatever they give you, for the worker deserves his wages. Do not move around from house to house. Luke 10:7
What do you make out of these two verses that seem to confilict?
I think the line is ok to depend entierly on your religous work for your support (as some of the apostles did), but not ok to become a religous huckser (like some well know tv-preachers who are more about merchandising.)
Where does Hal Lindsey fall? I don't know. Just because most of your work involves writing books (and telling people about them) doesn't mean you're a huckster. Writing still is the main way to get infomation across to people.
And it is the teachings of other than those that Paul is warning about.