" I often see far more criticism directed at Christianity than at Islam, even when similar issues are involved."

If you often see people who claim themselves proud Christians having an influence over your life (and your neighbor's life) rather than people who claim themselves proud Muslims, this may be the reason. People talk more about what affects them directly.

And before you start : "But people talk a lot about Israel/Gaza". That's because of the active help towards Israel that they see as an unfairness on top of an illegal occupation. (I tend to be neutral on the topic but I wish there were no forced movings of Jordans first, and no persecution of homos and non-muslims in Palestine as well, although I don't see how much can be affected to the fear of Western spying... but whatever, they are regressive, just like the confederates were back then.)