After five years of marriage, celebrity couple Tom Cruise, age 50, and Katie Holmes, age 33, ("TomKat") are calling it quits. Actually, Katie is calling it quits-while Tom was away shooting the sci-fi film Oblivion in Iceland, Katie secretly rented a New York City apartment and moved out. On Saturday, Tom's representative released this statement:

Katie has filed for divorce and Tom is deeply saddened and is concentrating on his three children. Please allow them their privacy.

Tom, who, in last month's interview with Playboy, spoke very highly and lovingly about his wife, was apparently caught off guard by the news.

Tom was also apparently caught off guard by the announcement that Katie is seeking sole custody of their daughter, six year old Suri Cruise. That aggressive move has the media pondering Katie's reasons for leaving Tom. According to Time Magazine, Tom's zeal for the Church of Scientology is at the root of the cause.

And it wouldn't be the first time Tom has let the Church come between him and his family. Tom married Nicole Kidman in 1990. Following their separation in 2001, Nicole moved back to her native Australia and Tom remained in Los Angeles. The couple's two adopted children, Isabella, age 19, and Connor, age 17, chose to live with their father.

At the time, the media speculated that the children's choice to live with Tom had something to do with the fact that both children "grew up heavily indoctrinated in the Church of Scientology, were home-schooled with scholastic emphasis on the tenets of religion, and grew up socializing with other high-profile scientologists." Nicole, who never converted to the controversial faith, has publicly expressed her sadness over the strained relationship with her children.

So is Katie just trying to stop history from repeating itself?

According to Time Magazine, Holmes "is reportedly eager to prevent...Suri [from] being indoctrinated into her father's strict Scientology beliefs." TMZ reported that Katie feared that Tom was planning on sending Suri to join the Church of Scientology's Sea Organization, "which functions almost as a religious order within the church"-Scientology boot camp. Long-time members and children of Scientologists as young as five can be sent to learn more about the religion without their parents.

Interestingly, this is not the first time the couple's religions have clashed. Katie's parents, who are devoutly Catholic, have questioned Tom, particularly with respect to their granddaughter. And although Katie converted to Scientology when she married Tom, Radaronline reports that "Katie wasn't exactly forthcoming with information during her Scientology audit/confessions."

Katie Holmes knew that Tom was a fervent Scientologist when she married him; recently, that fervour has been amplified.

Will Scientology play a role in the divorce of Tom Cruise and Katie Holmes?

Katie has reportedly become more and more concerned about the religion's influence on her daughter in recent years.

Now, Katie is seeking sole legal custody (permitting her to make decisions regarding Suri's education, healthcare, and religion) as well as primary residence. Katie filed for divorce in New York state, where judges tend to favour appointing sole custody to one parent to avoid children being placed in the middle of disputes.

Tom, on the other hand, has countered by seeking to move divorce proceedings to California, where courts generally prefer to award joint custody. US Divorce Attorney, Vikki Ziegler, told US Weekly that "usually sole custody is requested when a person either wants to hurt the other parent or has evidence of a parent being unfit."

Similarly, in Ontario, a court is unlikely to award sole custody unless one parent is deemed unfit or where the parents clearly will not be able to parent together.

Even in those instances, however, a court may hive off one aspect of custody and allow the non-custodial parent to makes decisions concerning that subject.

In Chauvin v Chauvin, for instance, the court ordered that decisions regarding the child's schooling should be hived off. In that case, the mother, who had custody of the children, moved the children to a new city and enrolled the children in an English language school, alleging that it was inconvenient to keep them in French school as they had been prior to the separation. The court deemed the decision of the custodial parent incorrect, and ordered that it was in the best interest of the children to continue attending French school. Accordingly, the court awarded the Francophone father decision-making powers over the children's education.

Generally speaking, Ontario has seen a movement towards joint custody. However, it is not enough that both parents acknowledge the other to be "fit" to parent; it must be in the best interests of the child for the joint custody order to be made. The fact that one parent professes an inability to communicate with the other parent does not, in and of itself, mean that a joint custody order cannot be considered.

However, there must be some evidence before the court that, despite their differences, parents are able to communicate effectively with one another. A court may also refuse to award joint custody: (a) where there is no evidence of historical cooperation and appropriate communication between the parents; or (b) if they are doing so only in hope that it would improve the parenting skills of the parent (Kaplanis v Kaplanis).

The question of whether Tom and Katie will be able to cooperate and communicate effectively is the decision of the court. Even where one parent opposes joint custody, as Katie does in this instance, joint custody may still be ordered. The overarching consideration is the best interests of the child (Warcop v Warcop).

The issue of who should be awarded custody of Suri will ultimately depend on the evidence of both Tom and Katie's parental roles, as well as the status quo established in the interim period. The decision will also likely be influenced by the jurisdiction deemed most appropriate.

If Katie is awarded sole custody, it will be an uphill battle for Tom to regain custody of Suri. In order to change an order for custody and access, the applicant must demonstrate a material change in circumstances, a relatively high threshold.