1. Is society getting worse?
Those that say no, will usually say that society appears worst because we are more aware of its problems because of increased ways to report these problems through social media, the internet, we're keeping better track of it, etc.
I'm not too sure about that though. I would think simple things to look at is family. Nowadays, divorce is common. It's rare to hear someone being married for 40 or more years. The school system seems disastrous with students not respecting teachers, and some teachers are crossing the line. Who we look up to sucks bad as well because the popular people (role models?) are a disaster. Some scandal seems to always be around the corner. And perhaps scandal adds to good ratings.
2. Is the decline of Christianity to blame for that?
I wouldn't say that it's just a decline of Christianity that's a contributing factor, but rather it's a decline in the type of system that Christianity and other religions tend to offer. Our morals, or the drives behind them, are too superficial. It's almost like politics (or what Jesus accused the Pharisees of being), where people do things as a public spectacle as opposed to doing it right from the heart. In other words, would these "good" deeds be done if no one else was looking or it wasn't self-serving? Not everyone falls into this camp of course, and that including non-believers, but it just seems the world is headed there more and more.
Politics is playing a bigger role in American society at least, and that's becoming a driving force for behavior even among people that aren't in political office. I suppose this group are taking their cues from politicians.