Legendary football manager Bill Shankly famously quipped that football was a much more important matter than life or death.
The former Liverpool boss's quotation could easily apply to followers of other sports in Ireland.
For fans of football, rugby, or gaelic games, the sport you support often defines who you are a quick look at how Rangers and Celtic fans across the north approach each Old Firm match proves that.
Followers of international football also behave differently than fans in other parts of the world.
Many Catholics in the north support the Republic of Ireland, while Protestants tend to follow Northern Ireland's team.
The differences are less obvious in almost all other sports where there is one Ireland international team.
In recent years Gaelic games have undergone considerable changes, most notably with the abolition of Rule 21.
Its removal in November 2001 means that members of the British security forces and police personnel in Northern Ireland can now join the GAA.
However, just one county in Northern Ireland, Down, voted in favour of removing the clause.
From these sporting irregularities, former University of Ulster professor Alan Bairner chose to edit a new book that examines these contradictions and issues.
Sport and the Irish came from a two-day conference at the University of Ulster two years ago.
Prof Bairner writes in his introduction that: "There is no denying the fascination that sport exerts in the Irish...psyche. Lansdowne Road, Croke Park and the Curragh are not places for the uninterested."
He said that the "deeply divided nature of northern society" has led to many writers looking at the relationship between sports in the Catholic and Protestant communities.
One of the contributors is David Hassan, a former inter-county Gaelic footballer and hurler in Derry and ex-Cliftonville footballer.
Mr Hassan, a lecturer at the University of Ulster in Jordanstown, looked at soccer, rugby union and Gaelic games, and the insight they give into how northern nationalists see themselves.
One of the arguments he suggested is how taking part in certain sports "can reflect a preferred future for the different sections of the nationalist people".
He argued that the debate over the abolition of Rule 21 highlights "the sizeable contrast in views between northern Gaels and their southern counterparts".
Mr Hassan claimed that there exists an "enduring sense of isolation" among GAA personnel in Northern Ireland.
He attributed this to the sport's experiences during the Troubles, when it was "often crudely portrayed as one part of a republican machine embroiled in a violent dispute".
Another factor in this was attacks on GAA clubs by loyalists up to and including murder.
He described one particular incident in which Wolfhounds GAA club in Limavady experienced problems with loyalist paramilitaries.
The club's chairman, Sean Bradley, said in the book: "(Loyalists) sprayed the pitch with chemicals to make a large Union Jack in the middle of the pitch.
"I would have received telephone calls saying that I would be shot dead."
Mr Hassan said that out of this culture, there came a contrast between opinions of the northern and southern Gaels, and only the "skilful leadership" of then GAA president Sean McCague led to Rule 21 being abolished.
He suggested that a reason why few northern counties voted for its abolition was a scepticism about the PSNI, even after the Good Friday Agreement.
He added that he believed the division between nationalists, north and south, will become "more pronounced" in years to come.
Moving his attention to soccer, Mr Hassan looked at the decision of northern nationalists to follow the Republic of Ireland rather than Northern Ireland's team.
He claims that nationalist involvement in football in Northern Ireland in the past has been one "of discrimination (and) injustice", citing the example of Celtic star Neil Lennon retiring from international football after loyalist threats.
It is against this backdrop that nationalists follow the Republic's side, a support that Mr Hassan said expresses "their support for the idea of Irish unification".
The author then moved his attention to rugby, a sport which "traditionally Catholics have not played ... in any sizeable numbers" but is increasing in popularity.
He contrasted this with the fact that the mainly Protestant supporters in the north have always supported an all-Ireland team.
He argued that the sport is a halfway house between Gaelic games and football, because of a cultural compromise on both sides of the community.
"A team that draws its players from Northern Ireland and the Irish Republic, one that contains both Catholics and Protestants, with its base in Dublin and the popular support of the Irish nation, north and south has much to commend it."
However, he added that many of the Catholics who take part are "viewed with suspicion" by some nationalists because of their involvement in a 'foreign sport'.
Because of the differences between how people see themselves across Ireland, Prof Bairner said he thought he should examine whether it has any significance on the sports they enjoy.
However, he added that his next project may be to look at how participants in the less popular sports, like fishing, see themselves.
Whether there are as many differences as the players of soccer, rugby and Gaelic games have between them remains to be seen.