At some point the Labour Party will have to decide: does it believe in religious freedom or does it believe in utilitarian government? Unless it does, it is heading for an almighty collision.

Yesterday, Ed Balls, the Schools Secretary, decreed that in future all 15-year-olds will have to attend a year of sex education classes, with detailed instruction on contraception, sexually transmitted diseases and gay sex. Any child who fails to attend will be treated as a truant and his or her parents punished accordingly.

There is a case to be made for compulsory sex education classes. The rate of teenage pregnancy is alarmingly high, even though the Government makes the problem look worse than it is by citing figures that lump 19-year-old pregnant girls together with 13-year-old ones.

But it is hard to see where Mr Balls’s decision fits with the Government’s aggressive laws against discrimination on the ground of religious belief. In any other context, denying people the right to express their religious beliefs has become a perilous business — just ask the King’s Cross hairdresser stung for £4,000 by an industrial tribunal last year for declining to employ a Muslim job applicant who said she would refuse to remove her headscarf while working in the salon.

As Mr Balls knows full well, there is a significant minority of parents who are utterly opposed on religious grounds to the idea of their children being forced to attend sex education classes. They are not going to be won round by any number of government statistics on teenage pregnancy. Rather, it will make them only more determined to keep little Moses or Ramesh safe from what they regard as the moral hell of sexual liberation.

There is only one way that Mr Balls is going to get these children into sex education classes, and that is to override everything the Government has previously preached on the right to express religious belief and effectively take the children of sex education refuseniks into state care. Yet as far as I am aware the Government has no plans to repeal the religious discrimination laws.

It is so obvious what is going to happen that I can almost write one of next year’s news stories now: “Parents sue education authority for forcing their children into sex education classes.”

As with the Luton schoolgirl Shabina Begum, who complained that a ban on her wearing a full-length jilbab infringed her human rights, the case will drag on through the High Court, the Court of Appeal and the Supreme Court, leaving taxpayers to foot a multimillion bill, before, eventually, a handful of judges will go off for a nice lunch and decide which of the government’s contradictory laws they prefer.

At the end of it we shall be left asking: why can’t the Government resolve the contradictions in its own laws? Lawyers are raking in a fortune from new Labour’s ideological and intellectual feebleness.

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