It’s remarkable how theologically conservative Catholics and Protestants have come to appreciate over the past 30 years, that on many theological and moral issues, they have much more in common with each other than with liberal members of their own respective churches.

Underlying this church-wide dividing line is a difference of opinion on the interpretation of Holy Scripture. Conservative Catholics and Protestants maintain that the plain text of the Bible, as understood by reason and the traditional teachings of their respective churches, is the ultimate authority on all questions of faith and morality.

Most liberal Christians also profess to uphold the primacy of sacred Scripture. Nonetheless, in practice, they use their reason to explain away the precepts of the Bible and denigrate the traditional teachings of their churches.

Consider how these contrasting liberal and conservative approaches have been applied to biblical appraisals of homosexual conduct, such as the passage in Romans 1:26-7, where Saint Paul relates people who knew God, but did not honour him, were given up by God “to dishonourable passions. Their women exchanged natural relations for unnatural and the men likewise gave up natural relations with women and were consumed with passion for one another, men committing shameless acts with men and receiving in their own persons the due penalty for their error.”

On the face of it, that passage seems clear: Paul maintains that homosexual lust and behaviour are dishonourable, unnatural and shameless. Peter J. Gomes, a professor of Christian morals at Harvard University and a typical theological liberal, disagrees. In The Good Book: Reading the Bible with Mind and Heart, he contends: “The ‘natural relations exchanged for unnatural’ among women, at verse 26, and among men, at verse 27, who ‘likewise gave up natural relations with women and were consumed with passion for one another,’ does not describe the conduct of homosexuals, but rather, of heterosexual people who performed homosexual acts.”

Thomas E. Schmidt is a theological conservative and specialist in biblical exegesis who holds an earned PhD from Cambridge University. In Straight & Narrow: Compassion & Clarity in the Homosexuality Debate, he devotes an entire chapter to the proper interpretation of Romans 1:26-7.

On the basis of a close study of the original Greek text in the context of the New Testament as a whole, Schmidt concludes that Paul’s profound analysis of the human condition in Romans 1 finds in homosexuality an example of sexual sin that falsifies our identity as sexual beings, just as idolatry falsifies our identity as created beings.

“Homosexual behaviour is ‘revolting,’ not because heterosexuals find it so – they have their own dirt to deal with (Romans 2:22) – but because it epitomizes in sexual terms the revolt against God. It is sinful, because it violates the plan of God, present from creation, for the union of male and female in marriage.”

Schmidt, of course, is not alone in taking this viewpoint. Numerous other conservative scholars concur. Their argument is so compelling that it has won over some eminent theological liberals such as Diarmaid MacCulloch, professor of the history of the church at Oxford University.

In his recent book, Reformation: Europe’s House Divided, MacCulloch notes that the debate over homosexuality “is an issue of biblical authority.” He adds: “Despite much well-intentioned theological fancy footwork to the contrary, it is difficult to see the Bible as expressing anything else but disapproval of homosexual activity. The only alternatives are either to try to cleave to patterns of life and assumptions set out in the Bible or to say that in this, as in much else, the Bible is simply wrong.”

MacCulloch has made his choice: as a sexually active gay man, he rejects the authority of the Bible and describes himself as no longer “dogmatically Christian.” Consistent with this viewpoint, MacCulloch has lauded Hans Kung, a liberal Catholic, as “a great Catholic theologian” and greeted the election of Pope Benedict XVI, a brilliant conservative theologian, as “deeply depressing.”

Such is the theological divide between conservative and liberal Christians, that if a faithful Protestant like Schmidt were to give his opinion, he would surely say that he feels a much closer moral and spiritual affinity to the Catholic Pope than to the Anglican apostate MacCulloch.