Notice that in:

"AS A GROUND FOR HUMAN DIALOGUE, I dispute both your premise 'there is only one truth' and your presumed opposite 'there are multiple truths.' Neither proposition correctly captures the state of the question about truth through human history."

Dennis changes the topic from truth - which is the existence of an objective reality outside our perception of it and correspondence of our subjective appreciation of it to objective reality - to the topic of consensus among humans on what is true.

This is a viewpoint prevalent at this blog - objective reality is irrelevant and what we feel about things is as important or more important than what they are.

Thus same sex marriage, gender flexibility, and abortion may all be "goods", while the reality of a natural law is denied, which of course denies a good portion of the divine law.