This is Interfaith Week, and many of my religious buildings across the country are holding similar services to this one. In most places, I suspect people will talk about the importance of respecting differences of opinion. You have your views, I have mine, but we can all get along. All religions have their own truths. It might be customary to say it, but I can’t bring myself to do it. Not all ideas have the same value. Some ideas are wrong. Some ideas are dangerous. Some ideas must be challenged as soon as we encounter them.

This week, we read a passage in the Torah with a violent history. In it, Jacob and Esau fight over who gets their father Isaac’s birth right. Jacob, the younger brother, tricks his dad into giving him his blessing. He dresses in his brother’s clothes, puts hair on his arms so that he’ll feel rougher, and puts flour on his tongue so that his voice will sound deeper. With the help of his mother, Rebekka, he kills an animal, makes some sweet meats and cons his father into giving him a blessing that was meant for his brother. When Esau comes in, Isaac is distraught to realise that he has given the blessing to the wrong son. Esau begs him to bless him, but Isaac insists that he can’t retract his blessing from Jacob. Instead, he gives him a new blessing: “You will live by the sword and you will serve your brother. But when you grow restless, you will throw his yoke from off your neck.”[1]

This story became more than a tale of sibling rivalry. It became the basis of bloodshed lasting centuries. Jacob took another name: Israel. As a person, he stood in for the whole of the Jewish people. Esau had another name: Edom. As a person, he became a symbol of Christianity and Rome. For centuries, that was the optic through which Jewish-Christian relations were viewed: as a struggle between two brothers for a blessing that could only be held by one of them. The Jews, Israel, insisted that they were the sole bearers of the blessing from God. Christians insisted that they had broken off the yoke of Torah when their Messiah came, and that they had replaced Jews as God’s chosen people.

This had real consequences for people’s lives. If Christians had replaced Jews, then Jews were a stubborn remnant of a bygone age; a people destined to be destroyed. St Augustine of Hippo, one of the Founders of the Church, argued that Jews should be allowed to live only as evidence, in their degraded state, of the superiority of Christianity. This story of Esau replacing Jacob was so influential on European thinking that, some argue, it helped to legitimate the Nazi genocide.

This month saw the five hundredth anniversary of the day that Martin Luther nailed his ninety-five these to the church door, demanding reformation of the Catholic Church. His ideas were so important. Luther was somebody who realised that ideas are powerful. He was responding to a time when the established Church used people’s fear of death to pay for a better place in the afterlife. The abuse of religion was creating a deeply hierarchical and unequal society. Luther wanted to challenge that. He realised that not every religious idea had to be respected. Sometimes they need to be resisted.

Luther was also a notorious antisemite. In his later life, he used his power as an academic to incite race riots against Jews. His ideas were adopted for centuries in justifying racist violence. When the movement he founded, Protestantism, gained the upper hand in Western Europe, his ideas were used to attack Catholics. Unfairly caricatured as automatons doing the bidding of the Pope, Catholics were denied access to citizenship, and imprisoned as foreign infiltrators, in many countries. Luther’s great idea – that religion should not be used to wield power – became subverted to serve its opposite purpose: of entrenching power.

Still, his ideas gave birth to our own religious movements. The Unitarians here draw their roots from Protestantism, wanting to take Luther’s best ideas to their radical conclusion of a religion grounded in equality and acceptance. Liberal Judaism, too, was inspired by Protestant reformation. Our forbearers wanted to create a Judaism without sexism or nationalism. Since then, we’ve tried to also create Judaism that embraces LGBT people and champions just causes like the rights of migrants and workers. I know that many of our Christian friends here share that ambition.

This leaves us with a question: how do we know if an idea is any good or not? If we’re not going to automatically respect differences of opinions, what grounds can we have for disagreeing without creating exactly the kind of competition between Jacob and Esau, that caused so many generations of suffering? I’d like to propose a test for conversations in interfaith dialogue: do our ideas support existing power structures, or do they resist them? Do they bolster the powerful or diminish them? There are questions on which we can agree to disagree – none of us knows for certain what God really is, or what the afterlife is like. But we can challenge our ideas about this world: do they make our world more just, more equal, more compassionate, and more peaceful? If not, can we really sanction them?

This, I would hope, could be the basis of a better model of interfaith. Rather than accepting differences, let’s challenge each other to live up to the best of the values we share. In the spirit of the prophetic tradition that has inspired us, let’s push each other to speak truth to power. The reformation brought about the idea that religion should not be wedded to power. Let’s take it to the next stage, and insist that religion be used as a weapon against power. Let’s work together to fulfil a religious mission of eradicating inequality, championing the cause of the oppressed, eliminating hunger and poverty, bringing about a world where all people are treated with the dignity they deserve. That would be a world that truly respects difference.

[1] Gen 27:40

This sermon was given as part of an interfaith service organised by Suffolk Liberal Jewish Community, and held in the town’s beautiful Unitarian Meeting House. After the service, an Anglican minister pointed out that I had not made clear that current Christian doctrine had tried to rid itself of its supersessionist ideology. I think it is important to note that much of the work challenging offensive ideas in Christianity has been done by Christians themselves, especially by Catholics at Vatican II. I am grateful to him for this constructive feedback.