Dr. Richard Mayhue has admonished those of us who engage in debate (specifically, debates about the end times, but most of his points are applicable to general biblical debate) by exposing the following poor tactics in a what-not-to-do list:

1. Putting non-biblical, historical documents on an equal par with Scripture to gain a greater sense of authority for one’s conclusion or even to refute a biblical presentation.
2. Reading current events into the Scripture to prove one’s point.
3. Inserting one’s predetermined position, without first proving it, into a Scripture passage to gain apparent biblical support.
4. Attacking the character of one who holds a particular view in order to discredit the view.
5. Accusing an advocate of an opposing view of holding certain unacceptable interpretations or beliefs, when in fact he does not, in order to demonstrate falsely his apparent poor scholarship.
6. Employing selective data to make one’s point, when full disclosure would have actually weakened the conclusion.
7. Drawing unwarranted and erroneous implications from the Greek NT text that are used to override the more obvious and determinative conclusions derived from the passage’s context.

- Master’s Seminary Journal Volume 13, 2 (Sun Valley, CA: The Master’s Seminary, 2002), 239-42.

Sadly, I see these methods widely employed in debates and about most subjects (except for number 2, which is mostly reserved for eschatological debates). That is sad because controversy and debate can be decidedly good things, clarifying doctrines which would otherwise remain obscure. However, the above list contain the behaviors which often render a debate useless.