A matter of principle
The Church versus the State, gay rights versus religious rights, Tony Blair versus most of his Cabinet... The row about adoption is a combustible mix. The curiosity is that it's been coming for months and that it's been allowed to reach this pitch.
When the Equality Bill was first being drafted the prime minister proposed an exemption for Catholic adoption agencies. The minister then in charge, Alan Johnson, resisted. A reshuffle led Ruth Kelly to take over control of the Bill. She joined Tony Blair in pushing for an exemption. Johnson now found himself responsible for adoption agencies as education secretary. He continued to resist. He was joined by Lord Falconer who - as the minister in charge of the law - argued that you simply couldn't have a law banning discrimination which allowed some people to go ahead and discriminate.
Peter Hain, the Secretary of State for Northern Ireland, also joined in as he was facing down protests in the Lords and Northern Ireland over their own version of anti-discrimination legislation (he has not, it should be noted, yet tabled specific proposals for adoption agencies). Others, including Jack Straw, joined the fray. Many around the Cabinet table see this as a core test of principle. Just as there could be no exceptions to laws banning signs declaring "no blacks" (or, indeed, Catholics) they argue that there should be no tolerance of policies which declare "no gays".
Downing Street now says the PM is looking for a "way through". There is no legal "way through" which I can see which does not risk either a Catholic or a Cabinet revolt. The government either has a ban on anti-gay discrimination or it does not.
So, what is he up to?
Ruth Kelly is looking for a practical way to avoid the loss of adoption services on April 6th when the Equality Act comes into force. She believes that the Catholic adoption agencies want to find a way through and are desperate to stay in business finding homes for some of the hardest children to place (although they only handle 4% of new cases, I'm told that they take on around a third of all the toughest cases). She is examining a long transition period to allow Catholic adoption agencies to change policy, merge with other non-Catholic agencies or to close in an orderly way.
What's striking about this row is how it is driven by a clash of principles and not by practical problems. There are relatively few gay adopters and only a tiny number choose to go to Catholic agencies (more, of course, might come forward if they were confident that they wouldn't be discriminated against). However, both sides are determined to assert their rights and to go straight to the courts to test them. What's more, a newly-assertive church is, I sense, planning other stands to defend its rights.
The tension between religious views and political principles is embodied in the prime minister himself. It is a sign of how serious this argument has become that he is being condemned by some for putting his own beliefs and those of his Catholic wife, Cherie, before Labour's commitment to equality.
It's a sign too - yet another one - that he no longer provokes fear or loyalty in a growing section of his party.