The Prime Minister may have wimped out of the debate in the House of Commons this afternoon, but it is his fault, or achievement, that gay marriage will almost certainly reach the statute book before the election. In making this happen, I don't think he will inflict permanent damage on his party, in which the division of opinion is mainly along generational lines and will shift with time. For the Church of England, however, tonight's overwhelming vote was a disaster: it will be forbidden by law to conduct same-sex weddings that many of its clergy would like to see written into their prayer books. The House of Bishops' already wobbly consensus on this issue will fall apart once some prelates start turning a blind eye to gay church wedding ceremonies disguised as "blessings". The legislation will set diocese against diocese and parish against parish; the "lock" banning gay weddings in the C of E will not survive changes to the demography of congregations, in which age will count for more than churchmanship. Many young Anglican evangelicals either support gay marriage or are lukewarm in their opposition to it – as the new Archbishop of Canterbury is no doubt well aware. Yet, even far into the future, there will be a solid rump of Anglicans fervently opposed to homosexual marriage on theological grounds. If you thought the battle over women priests and bishops was nasty, wait until this one begins.