The Bible:
Thus saith the Lord, Learn not the way of the heathen, and be not dismayed at the signs of heaven; for the heathen are dismayed at them.
For the customs of the people are vain: for one cutteth a tree out of the forest, the work of the hands of the workman, with the axe.
They deck it with silver and with gold; they fasten it with nails and with hammers, that it move not.
Jeremiah 10:2-6 (KJV)
Quote Source: Bible Gateway
If all the truly faithful were all to stop what they are doing and read the bibles they believe to be holy text start t to finish, many of them would realize how ridiculous their religions were and not only that but they would realize how many rules they break on a regular basis and probably start to seriously question the validity of their faiths.
For a long time the catholic church knew this and had to write their own version of the bible before they would let their faithful read it. Now a days you can read their bible the Holy Bible according to the Catholic Church simply called the Holy Bible by them and you will find even after all that it's still loaded with ridiculousness because the editing they did was to remove things they did not want their parishioners to read.. I think this more than anything else we have in history is a sign of the ever increasing human ability to reason. In the future I suspect the holy text will get revised again and again as time goes on, thus is the evolution of religion.
As we (the human race) continue to get better at critical thinking these text loose more and more validity but what probably fuels the atheist more than anything is the blatant ignorance not only of other cultures but also of the ignorance ideologies of the religions the supposed followers have of their own faiths and the constant disregard the display on a regular basis to what they profess to believe.