There are a lot of religious folks on this thread who are upset that "Atheists are too loud and too mean". This is really an attitude born of privilege and of assigning a special status to religion. If I were to make an argument that pointed out a flaw in some mathematical or scientific discussion, or even one that disagrees with your politics, and even if I used some heated language, (almost) nobody would say that I'm being too loud or too mean.
The difference is that religion has traditionally been granted a special, protected status, that no other school of thought or group of people receive, which prevents it from being criticized. So, to a person who is used to hearing nothing but praise for the virtues of religion in their community, reading even a calm, well reasoned criticism of religion on the internet strikes a religious person as unacceptably harsh.
To verify this, let's do a simple thought experiment. Imagine you read "How could anybody ever believe that Jesus was born of a virgin? That is absolutely absurd!". If you're a Christian, your blood may be boiling just reading that. Now, imagine you read "How could anybody ever believe that Pluto isn't a planet? That is absolutely absurd!". Almost nobody is likely to be genuinely offended. The structure and tone of the statements is identical. Both are evaluating the truth value of a factual (correct or incorrect) assertion. Yet the perceived tone is likely to be completely different for a religious person.
The difference between the two statements, of course, is that one is criticizing a religious belief and one is criticizing a secular belief. In other words, the perceived "loud, mean" tone of the first statement is not inherent in the actual tone of the statement. The difference is in the special, protected nature of religious beliefs and the fact that they generally enjoy complete immunity from criticism.