What does it mean if you are speaking like you are 'delivering a sermon'

What does it mean if you are speaking like you are 'delivering a sermon'

I recently delivered a speech. When given feedback, I was told the following:

You do have a tendency to fall into a rhythm and intonation that can sound like you are delivering a sermon – be careful with this.

What does this mean? I was told my pitch was already very good, so what should I do to address this feedback?

I associate sermons with a sing-song yet repetitious tone. Difficult to describe so here is an example.

The Most Boring, Ordinary Sermon - https://vimeo.com/275689798

Note also that sermons are intended to present the truth. There is supposed to be no question that the facts are correct.