Last month’s highly public split over gay marriage shifted to Australia the spotlight on the issue bitterly dividing Christian and Jewish communities worldwide.

The greatest revision of belief within the Judaeo-Christian faiths since the Reformation is underway. It is a bruising process with skirmishes erupting regularly around the globe. Conservatives are still winning, but progressives are gaining rapidly.

Six Roman Catholic bishops in Victoria wrote to their flock in late March urging them to lobby politicians with their views on same-sex marriage. This was in response to proposed legislation in Australia’s federal Parliament to extend marriage to gay couples.

“A grave mistake will be made if such legislation is enacted,” the bishops warned.

In response to this 77 other faith leaders produced a contrasting letter urging Christians and Jews to support the marriage reforms.

Signatories included respected Evangelical elder statesmen, Jewish Rabbis, a Buddhist priest and prominent clergy from the Uniting, Anglican, Apostolic Johannite, Quaker, Metropolitan and other churches across Australia.

These letters are significant both for Australian politics and the future of the religious bodies.

The second, progressive letter effectively neutralises the impact of the first on any wavering MPs. Hence this lessens the pressure representatives have been under in the past to maintain the marriage status quo.

This pressure has been substantial in Australia and elsewhere. The five European nations (out of 38) which have legislated to ban same-sex unions – Lithuania, Moldova, Monaco, San Marino and Vatican City – are those most under Catholic or Orthodox influence.

For the churches and synagogues, the shift towards accepting gay couples into membership is of monumental importance. These religious bodies are effectively acknowledging they have been condemning people to hell for centuries – wrongly. Oops!

For the conservatives resisting this reformation, the stakes are just as high: to change now is to cave in to the liberal secular lobby and abandon the true faith practised for 2000 years. Longer for the Jewish community.

Four factors are impelling this shift towards accepting same-sex unions.

First, from science. Genetics, human physiology and psychiatry have shown that same-sex orientation is natural, healthy, not reversible, not contagious and poses no threat to anyone. From anthropology and sociology we know about four per cent of the population are homosexual and another small percentage bisexual. And has been so forever.

Paediatrics and behavioural sciences have shown same-sex parents are just as effective as straight parents in child-rearing outcomes. Zoology has confirmed that a small discrete percentage of same-sex couplings occurs in all gregarious bird and animal societies.

So if gay sex did not originate in San Francisco in 1969, but is a normal part of God’s diverse creation, why does the Bible condemn homosexuality? Okay, dopey question for rationalists. But a critical one for people of the Book.

Which brings us to the second significant recent shift: the biblical texts.

Jews and Christians believe God reveals his truth through both nature and Scripture. The two cannot be contradictory as God authored both. History has taught painfully that when they appear to conflict, science has been right and Scripture wrong.

Or, more correctly, the traditional interpretation of Scripture has been wrong. Revolving Earth or sun, schizophrenia or demon possession, evolution or creation in six days. All ferocious bouts between science and the Bible which science won by knockouts.

Hence there is a willingness today to admit to error which has not always been apparent. Okay, some denominations are yet to abandon infallibility completely, but a shift is underway.

Biblical historians now increasingly think that the Bible condemns homosexual rape, temple prostitution and coercive or abusive acts. But not loving, monogamous same-sex unions, as previously misinterpreted.

One-man-one-woman marriage is clearly not the only option in the Judeo-Christian texts. Polygamy and concubinage are fine in many situations. The intense love affair between David and Jonathan is nowhere condemned. Nor are any of the other biblical same-sex unions. The evidence of Scripture today – as with the natural law – suggests God is cool with variations.

The third area of discovery is in church history where heterosexual marriage has not been the only approved union. The very early church actually advocated celibacy and only reluctantly approved any partnership at all. Not until the 12th century did marriage become a sacrament. One-man-one-woman marriage as we know it today dates from the 16th century.

Yale University’s Professor John Boswell unearthed controversial evidence in the 1970s that condemnation of same-sex unions is actually relatively recent. The church in earlier times, he claimed, accepted and celebrated them.

So when the six Australian Catholic bishops say “the Government cannot redefine the natural institution of marriage, a union between a man and a woman”, fair questions today are “what natural institution?” and “why not?”

The fourth, and for some the clinching discovery, is that gay and lesbian pastors, teachers and leaders actually do a great job. As do LGBTQ congregation members as they participate more and more.

These four factors are leading many Jews and Christians worldwide to welcome LGBTQ people and support gay marriage. It is not yet a majority. But heading that way.

In May last year the conservative Presbyterians accepted gays in ministry in both the USA and Scotland. Other denominations are following.

In the Roman Catholic church pressure is building. Change is being urged from within. The matter of active homosexuals in the priesthood is now in the open. The impact of legitimate gay marriage on recruiting priests is being discussed. But no-one expects doctrinal reversal soon.

The world is changing. Churches and synagogues are changing. The battles, however, have a way to go.

Alan Austin is an Australian freelance journalist based in France. This article first appeared on onlineopinion.com.au, reproduced with permission.