A favorite pastime of many people who seem to have certain common characteristics, such as:
Now, let me elaborate on these points a bit.
Limited exposure to limited religion
It is simply amazing how little so many people, including some highly educated people know about religion. Indeed, this is true of many very religious people, especially in the US.
This has probably something to do with education. There are essentially two types of school in the US: public and religious (yes, I know there are other types, too, but these two seem to be the most common).
Public schools do not teach any religion (nor should they IMHO).
Religious schools generally were started as a reaction to public achools, and only teach their own religion.
Hence, limited exposure to limited religion. (Please understand, I am not criticizing this sytem, merely describing it.)
A conviction that all religions are essentially the same
This is probably a result of the limited exposure described above. How is anyone supposed to know that religions are so different, when one is only familiar with one religion? And when so many religions perform the same (or similar) outward ceremonies?
How is, for example, someone exposed only to a specific Christian religion supposed to know that the Buddhist who prostrates himself in front of the statue of the Buddha is not falling down in fear of a deity? How is a (former) Baptist supposed to know that a Catholic kneeling in front of the statue of Virgin Mary is not worshiping idols?
A lot of misunderstanding!
A strong belief that religion and faith are essentially the same
Well, again, for some people it is; for many it is not. Depends on the religion. Some are very faith based, others are extremely intellectual (take a look at Thomas Aquinas for an example), others are very mystical, emphasizing inner experience.
The idea that all religious people are mere followers
Well, many are, no doubt about that. And they tend to be quite vociferous about their beliefs. That does not mean all are, nor does it mean the majority are.
You might be surprised what they taught us at Gregorian University, for example. That is the top Catholic university I happened to study at when I was a Catholic priest. Sure, all they taught us was Catholic. But what a variety of opinions they taught us. And they encouraged us to think, to come up with our own ideas! Indeed, it is part of Catholic moral theology that if your personal beliefs are in conflict with the official teachings of the Catholic Church, you must go with your beliefs.
Or take the Buddha's encouragement not to believe anything just because he said it.
Inner doubts about their own convictions
Now this one may sound controversial, but it is not.
People who are comfortable with their personal beliefs rarely have a need to bash. It makes no difference if they are religious and bash other religions, or the atheists, or whomever else; or they are non-religious and bash those who are.
People who are not sure about their convictions often feel the need to bash and proselytize. By finding converts or birds of the feather, they get an external assurance that they are right after all.