Now many places are seeing a demand for religious materials as more people are turning to religion searching for answers.
Religious leaders and bookstores say that in times of tragedy, people return to religion.
Religious leaders from several different faiths gathered at Milwaukee's Red Arrow Park Wednesday for the same cause -- to pray for the safety and security of our country and military troops who have been called for duty.
"Almighty God, bring justice to our life, bring peace to our life," Amin Amer of the Islamic Society of Milwaukee said.
Since the terrorist attacks Sept. 11, people have turned to religion.
"If religion does anything, it does a give people a deep sense of hope and seeing the larger picture," Milwaukee archdiocese Archbishop Rembert Weakland of the Milwaukee Archdiocese said.
Churches aren't the only places packed. People are also flocking to bookstores looking for religious materials.
Bookstores, nationwide and locally are seeing an increase in Bible sales.
Pro Bo Calls on 19th Street and Wisconsin Avenue has seen a 25 to 35 percent increase in Bible sales.
"We ran out of these this past weekend and people are very interested in that," John Fisco of Pro Bo Calls Bookstore said.
There's also an interest in the Koran and Islamic faith, one that teaches peace and mercy for all mankind.
"People are interested to know what is the real message of Islam, what is the real perspective of Islam regarding what happen and what Islam stands for," Amer said.
Whether its about Islam or Christianity, many are searching for answers in this crisis.
"Always out of terrible things come something good and we think what is good about it that more people would like to learn about each other," Amer said.
Bookstores also told WISN 12 News that people are buying materials about President Bush (news - web sites) and Attorney General John Ashcroft (news - web sites) that talk about their religious faiths because people want a better understanding of what they stand for and believe