The second reason is that Christianity is attacked is that it is true. Jesus really is the Son of God. He really did die for our sins and He really did rise again on the third day. He really is the Way, the Truth, and the Life.
It is politically incorrect to say that, but taking offense to the truth does not make it untrue. People resent the claims that Jesus makes on their hearts and their lives. They want to be their own little gods, but they are unwilling to admit what that means. So … they attack the only hope they have.
Pope Francis talks about satan more than is politically correct, even for a Pope. But he is right to do this. Christianity is attacked because it is the Light, and the darkness hates it.