As I have been informed, at the time and in the regions of Gautama Buddha, there was a culture sophisticated in debate, with community debating halls in ?every? community. There were also apparently customs of experienced spiritual practitioners challenging each other to debate. These encounters were vigorous, apparently of great public interest, and greatly affected reputation in these communities. I think DN16 is directed towards these activities.
But now we don’t have such culture, and it’s actually illegal in many places to challenge people’s religious beliefs in public; it is defined as harrassment, prejudice, blasphemy, hate speech, etc. So it might be inappropriate in general public now. Breaking laws or breaching customs of civility is not AFAIK something the Buddha allowed, as it endangered the existence of the Sangha, and the preservation of the Dhamma; nor is it required or even perhaps congruent with the Noble 8 Fold Path.
“And what is right speech? Abstaining from lying, from divisive speech, from abusive speech, & from idle chatter: This is called right speech.”
— [SN 45.8]
"Monks, a statement endowed with five factors is well-spoken, not ill-spoken. It is blameless & unfaulted by knowledgeable people. Which five?
“It is spoken at the right time. It is spoken in truth. It is spoken affectionately. It is spoken beneficially. It is spoken with a mind of good-will.”
— [AN 5.198]
"One should speak only that word by which one would not torment oneself nor harm others. That word is indeed well spoken.
“One should speak only pleasant words, words which are acceptable (to others). What one speaks without bringing evils to others is pleasant.”
— [Thag 21]
"Abandoning divisive speech he abstains from divisive speech. What he has heard here he does not tell there to break those people apart from these people here. What he has heard there he does not tell here to break these people apart from those people there. Thus reconciling those who have broken apart or cementing those who are united, he loves concord, delights in concord, enjoys concord, speaks things that create concord.
"Abandoning abusive speech, he abstains from abusive speech. He speaks words that are soothing to the ear, that are affectionate, that go to the heart, that are polite, appealing & pleasing to people at large.
"Whenever you want to perform a verbal act, you should reflect on it: ‘This verbal act I want to perform — would it lead to self-affliction, to the affliction of others, or to both? Is it an unskillful verbal act, with painful consequences, painful results?’ If, on reflection, you know that it would lead to self-affliction, to the affliction of others, or to both; it would be an unskillful verbal act with painful consequences, painful results, then any verbal act of that sort is absolutely unfit for you to do.
There’s more on this topic at