Theists in general have a different conception of proof than those of us who are not believers. They allow subjective experiences to count as evidence of their beliefs. These range from the tingling sensation they may feel when they read the bible or sense God's presence, the so called "small voice" in their heads that guides their every action, or what the rest of us may call a gut feeling. Based on all of these fallible experiences they claim that they have an inside track to knowledge that is not accessible through any other means than through the acceptance of the concept of faith. This is the source of their arrogance!
According to the Mirriam Webster online dictionary arrogance is defined as : 'an attitude of superiority manifested in an overbearing manner or in presumptuous claims or assumptions' http://www.merriam-webster.com/dictionary/arrogance based on this definition atheists cannot be considered arrogant for several reasons. The main reason is that what we claim is not based on faith but known facts gathered through science and just our everyday observation of how things work in the natural world. We can explain most natural disasters through natural means without trying to rationalize why a god would do or allow such a thing to occur.
Natural disasters are not God's way of punishing idolaters or unbelievers nor is it a way of testing his faithful flock. We don't try to make sense of the world through the use of ancient superstitions and myths. On the other hand Jews, Christians, and all other religious believers all claim to be right about their beliefs basing themselves on faith and what they believe through subjective evidence to be true. Christians and Jews in particular take it a step further by demonstrating that they have a superiority complex based on their special status as believers. The bible backs this up in both the New and Old Testaments.
In Psalm 14:1 it says: ' The fool has said in his heart, 'There is no God.' Their deeds are corrupt and vile, not one of them does right.' According to this verse and many others like it all unbelievers are corrupt and vile in deed and since we don't do right I guess that would also make us immoral. The New Testament says in 2 Corinthians 6:14,15 that: 14 Do not harness yourselves in an uneven team with unbelievers; how can uprightness and law-breaking be partners, or what can light and darkness have in common?15 How can Christ come to an agreement with Beliar and what sharing can there be between a believer and an unbeliever? This text and many others like it apply to fraternizing with unbelievers and relationships.
Do not let anyone deceive you with empty arguments: it is such
behaviour that draws down God's retribution on those who rebel against
him.7 Make sure that you do not throw in your lot with them.8 You were darkness once, but now you are light in the Lord; behave as children of light, 9 for the effects of the light are seen in complete goodness and uprightness and truth. Ephesians 5:6-9 (NJB).
Passages like these help to pinpoint the source of the prejudice displayed by believers against atheists and also demonstrates why many believers think that there is no such thing as morality without God. It is just one of the many examples of intolerance shown by believers towards those that don't share their beliefs. Those of us that don't believe as they do walk in darkness and could not possibly see till we accept those beliefs and submit our lives to the imaginary Lord of creation.
In conclusion, I think that I have demonstrated that Christian arrogance is a fact and that it is also supported by their source of their beliefs the bible. It is this special position of prominence that is given to them by their imaginary guy in the sky that gives them this feeling of superiority properly defined as arrogance.