What is the motive behind christians saying this?

i've heard SO many, like..SOOOOOOO many christians talking down catholics, it's incredible. i mean, doesn't that mean they aren't being "christian"? "Catholicism is just a culture, not a religion!" or "Catholics don't even read the bible!" ohhh my. i feel like punching people in their throats when they say that. Not only are they being ignorant, they're being hypocritical. When i was religious, i carried my bible to school. i was a catholic, and i knew so much more than those "christians" about christianity. JUST SAYING. try to watch what you say, i mean, you are all worshiping the same deity. does it really matter to you how you do it? or, better said, how someone else does it? i don't understand what they are hoping to accomplish by saying this..