Tom Cruise and Scientology are a package deal, and because Katie Holmes reportedly never truly bought into it, the religion is believed to have played a big part in the divorce.

REUTERS/Mario Anzuoni

hen Katie Holmes abruptly filed for divorce last week from Tom Cruise, her husband of five years, reports quickly began to surface linking the actress' decision to her increasing discomfort with the role of Scientology in the family's life. (Neither Cruise nor the church has publicly addressed the broader issues behind these reports.) The marriage "began with Cruise's leap onto Oprah's couch, and will end with a renewed public interest in Scientology, the controversial religion the pair shared," says Maura Judkis at The Washington Post. So what is it about Scientology that reportedly caused Holmes, who converted to the religion in 2005, to want out now? Here, a brief guide: 

Was Holmes ever into Scientology?
Reportedly, yes. Cruise is one of most high-profile Scientologists in the country, and convinced Holmes to convert to the religion before their wedding in 2005. At first, reports The Daily Beast, Holmes was game, even allowing a church representative to accompany her to a W magazine shoot soon after her coupling with Cruise, and refusing to answer any question the representative didn't approve of. But she eventually became exasperated with the restrictive religion, and "reportedly hadn't been seen inside a Scientology Church for some time." She even enrolled her daughter, Suri, in a Catholic preschool. 

What role did religion play in the divorce?
The truth is, "Katie has never been fully committed to Scientology," says TMZ, and the divorce was likely spurred by arguments over how significant a part Scientology would play in Suri's life. Holmes was reportedly persuaded that Cruise would force Suri to enter the "ultrazealous Scientology group called Sea Org," says New York's Daily News. Perhaps cutting ties with Cruise was the only way to protect Suri from the religion, says The Washington Post. 

What is Sea Org?
Sea Org stands for Sea Organization, a religious order within the Church of Scientology that former members describe as entailing an "odd mixture of military and corporate management styles," says Judith Welikala at TIME. The group is mostly populated by the church's most veteran members and their children, and kids as young as 5 join the group — sometimes without their parents' accompaniment. Members are reportedly obligated to sign a billion-year contract "to demonstrate their commitment to the organization." Holmes is expected to seek sole custody of Suri and remove her from the Scientology-linked New Village Leadership Academy, which she currently attends, to protect the girl from Sea Org. 

How is the church reacting?
There have been numerous reports that members of the church were tailing Holmes in New York, driving the actress into a state of paranoia, says the New York Post. After several cars followed her all day, Holmes reportedly called the police out of fear that members of the religion were planning to abduct Suri. Church officials have denied that they were following her. Still, Holmes fired almost the entire team that worked for her while she was married to Cruise, including her former publicist and the security detail that was hired for her by her husband. 

Sources: Daily Beast, Daily News, NY Post, TIME, TMZ, Wash. Post