Why does it make you suspicious? Do you have legitimate grounds for this? Under the CPC, extreme poverty has been eliminated, and China went from being one of the poorest countries on the planet to a rising superpower in less than a century. When you look at the real, material change in people's lives in as short a timespan as this, it's understandable why they have a high approval rate.
Secondly, I don't know what you're referring to as "justification for violence and oppression."