The difference between a sermon and a discussion

A sermon is essentially a speech provided to an audience where discussion doesn't happen. You present your point of view and leave. You don't take questions and you don't invite criticism of your point of view.

So how is this different than a discussion? A discussion is a two way conversation. Substantive discussion requires both sides to present their point of view and generally involves a back and forth process which involves the expectation of both sides answering relevant questions.

Now let's look at the contract that every person tacitly agrees to when they start a thread in this group. The foremost sentence says:
Discuss religious and theological issues.

It should go without saying this is the SOP for this group and the TOS for DU requires compliance with all SOPs. Now we all know this isn't well enforced. We've all seen the drive-by posts where someone posts a provocative subject matter and then abandons the thread never to be seen again. So this is one level of dishonesty. Another level of dishonesty exists when a person pretends to discuss the subject, but flatly refuses to engage in anything remotely resembling a good faith effort to discuss the subject. This usually takes the form of recognizable fallacies like whataboutism or may even rise to straight out ad hominem. When this happens once or twice you might be able to write it off as oversight and intellectual dishonesty, but when someone engages in that behavior over dozens, if not hundreds of threads over a long period of time, it's hard not to get a sense there's some pretty high level fuckery going on.