Writing laws to govern human beings is not easy. Bright line rules never seem to work, but there are certainly moments when consistency across potentially divergent realities is necessary. Our laws simply cannot be designed to take into account every exception or contextual reality. Laws will never make everyone happy. It's just not possible. Laws canot match human complexity and still be effective.
The motivation for legal exceptions must be consdiered, along with many many other contextual variables. Often the motivation for seeking exceptions is not to make a law more likely to succeed, but instead to render it as ineffective as possible. A key distinction needs to be understood. It is essential to consider as many contextual variables as possible in making laws, but decisions always have to be made as to which distinctions will be taken into account and to what extent. Law making is a balancing act. General goals (prevention, punishment, etc.), issue specific goals, values, and means must all be weighed against one another. This is a complex process, as the variables are interconnected and the actors seldom impartial.
Across the pond, the Catholic Church would like to be excepted from The Equality Act, which would forbid them from refusing to place children with gay couples. The basic argument appears to be that where conflicting rights exist, exceptions should be built into the laws. In this case the conflict is between the rights of gays to adopt and the rights of Catholic,s and the Catholic Church itself, to believe that homosexuality is evil and act upon that belief in their approach to adoption and their management of adoption services. If only for practical reasons, the views of the Catholic Church, and other churches, should be considered. In the end, however, the request of the Catholic Church for an exception to the Equality Act should be rejected. A phased implementation could be considered, but seems a little silly given the numbers of homosexual couples seeking adoptions facilitated by the Catholic Church. The attempt by the Church to blackmail lawmakers by threatening to end their services should be ignored. In this situation the importance of granting equal rights to homosexual couples, and teh importance of finding families for children, outwieghs the need to respect the belief on the part of Catholics that they don't deserve equal rights, and actually are destined to go to hell. Christian churches held similar beliefs about slaves, non-whites, and non-Christians at earlier moments in history. The only reasons for accomodating such 'rights', are practical. And practical considerations, such as the impact of a Catholic boycott of all adoptions, must be weighed against: competing practical considerations (would the Catholic church follow through on its threat, what kind of public backlash would be visited upon them, etc.); the precedent being set and it's future impact; the rights being compromised; the proper place of religion in British society, etc. A whole separate set of considerations faces Catholics and Christians in their consideration of this issue.
What is most important in this, and any political issue, is the balancing of contextual factors. A good decision will only result from a complete and critical weighing of the factors involved, and the ability to make hard decisions between competing concerns. I believe that the proper decision in this case would be to reject the inclusion of any exceptions for Catholics, but to allow for a phased implementation. I believe that this decision is proper because it is the outcome of the proper decision making process.