Question

What is the subject and the verb

Don't you think we've lost that truth in this society of ours?

Answer 1

Subject: we

Verb: have lost

"don't you think" is just an additional phrase added on to the beginning. The meat of the sentence is that we have lost the truth. Everything after "truth" is additional prepositions.

Answer 2

Verb: Lost

Predicate: In this society of ours.