Why do some people feel the need to be openly antagonistic to Christians?

I am personally agnostic. I have never attacked anyone about their religion. I may ask a few questions in order to gain a better understanding of a person's views, but these are solicited. My issue, which will make me get on the offensive, is when a person is aggressively pushing their views on me. I am open to discussion and will go point for point with someone. I have also never seen this shark feeding frenzy that you have addressed, but I can see that it could happen. I have full respect for peoples faiths, that's one of the things I fought to protect.

I can't speak to the motivations of others but I will recount an anecdote that I think is a root cause, although the exact situation is unique I suppose.
Last year I went to the MPD on my post early in the morning to replace a worn ID. In front of me in line were two Humanist chaplains from the Royal Netherlands Army. The ID card section worked with it's usual alacrity and I got to listen to about 20 minutes of the civilian alternating between berating the KL chaplain and having him explain his point of view. It was pretty offensive to me because she seemed openly antagonistic and he was our guest, both to our country and our Army. If that was MY first impression of American Christendom I'd be pretty antagonistic too.
To his credit the guy was very patient and thanked her for her time and left.

American Christians in particular seem to feel the need to be openly antagonistic on their own and historically have been. I think what you are describing is a modern backlash. I think you will also find that historically speaking Christians have been intolerant of differences in opinion within their own ranks, murderously so, and in this century. Any outsider, especially someone who doesn't share your faith would be logically skeptical, and militantly so.

Listen, if you are a christian believer, then you should abide by the Bible.

It plainly states that, basically, you should worship in private and not to make a big deal about it. As in, it is between you and your god, no need to advertise it to the world.

I feel religious people of all denominations like to go against this simple advice and advertise their religious colors.

Believer or not, keep it to yourself and congregate with your church if you must, end of story, chances are the belligerence would diminish.

I am not an atheist, I simply keep my religion to myself and do not proselytize.

Isn't it obvious that religious questions here on RP or elsewhere inevitably end in discord? Why not simply stop asking or trolling for religious enmity?

Good night everyone.

People hate the truth

I kind of commented about this earlier on a separate post, but here is one possibilty (and I say one because it is about me and my actions are mine alone, not the actions of others). I was an Atheist converted to Catholic during my first tour in Afghanistan. Without getting into how that happened here, when I was an Atheist, I made it my personal mission to disprove the beliefs of all religious people, most particularly Chriatians. I didnt do this because I hated them or that I actually believed Atheist views weee better then religous ones. I did this because I was angry at God, hated the church and couldnt stand the crape I was feed as a kid by my Mothers extremist church groups. I generalized all Christians under the actions of the few that did me wrong. Just like I shouldnt have generalized then, I ask that you don't generalize the above identified actions as anything other then my own.

Personally, I try not to "attack" people for their religious beliefs. I will feel free to chime in on a discussion thread. In individual conversation, I will (usually) only talk about my beliefs if someone else brings it up. And then I will try to explain my position without being insulting...but without being apologetic and with extreme prejudice against the notion that religion "requires" reverence by non-believers.

Where it comes up for me most here on RP, is that I will take EVERY opportunity to attempt to remove references to any religion (see? Non-discriminate) from official things (policy, ceremonies, decorations...basically, anything that isn't specifically "yours" to do with what you wish).

Since Dr. Dawkins is mentioned by name in this question, perhaps his words might have some relevance here...

http://www.theblaze.com/stories/2015/05/15/evolutionary-biologist-richard-dawkins-slams-young-earth-creationists-i-said-id-never-despise-individuals-just-their-views-but/

It's their own fear that causes them to be on the offensive. I'd rather be Christian and be wrong than the other way around. Eternity is a long time. Besides, as I heard it said in a movie once - Why is it the vast majority of the worlds population, regardless of faith or religion, believe in some sort of supreme being or higher power?

It feeds their ego to condescend to people they have a chip on their shoulder against.