"It is impossible to pass silently by the liberalism and relativism which have become so characteristic of today's Anglican theology," declared Archbishop Hilarion Alfeyev in 2010 at a dinner hosted by the archbishop of Canterbury, Rowan Williams, at Lambeth Palace.
Condemning women's ordination and blessing of same-sex partnerships by some churches, he stated that "we seek and find allies in opposing the destruction of the very essence of Christianity".
Metropolitan Hilarion of Volokolamsk is a Russian Orthodox, not an Anglican, archbishop, chairman of the Moscow patriarchate's department for external church relations.
Yet arguably he and his Roman Catholic counterparts have influenced the Church of England and wider Anglican communion to an extent that few can match, slowing progress towards the inclusivity which many feel is essential in living out gospel values and sharing the good news of Christ in today's world.
The ecumenical movement has brought many benefits, for instance enabling ancient doctrinal divisions to be overcome and joint action on problems like global poverty and militarism.
The Church of England is part of the Porvoo Communion, bringing together several European churches in full communion.
Yet for Williams, deepening such bonds has taken second place to pursuing closer relationships with the Roman Catholic and Eastern Orthodox hierarchies.
Originally a progressive Anglo-Catholic who supported the ministry of women and gay people and a brilliant scholar, he has long been fascinated by the Orthodox church and its rich spiritual heritage. His doctoral thesis was on Orthodox theologian Vladimir Lossky, and he has also written on icons and Russian writers Bulgakov and Dostoevsky.
When he took office, he soon came under pressure from fellow Anglicans – largely conservative evangelicals – to support a more centralised structure for the communion, up till then a family of autonomous churches, and oppose equality for lesbian, gay, bisexual and trans (LGBT) people. But this was reinforced from a different quarter: the Vatican.
In visits to Rome in 2003 and 2006, and on many other occasions, he was urged to act on these issues and women bishops.
The Eastern Orthodox church suspended dialogue with Anglicans after a partnered gay man became a US bishop, increasing the pressure.
Cardinal Walter Kasper, president of the Vatican's council for promoting Christian unity, was invited to speak at the 2008 Lambeth Conference of Anglican bishops, and took the opportunity to condemn moves towards greater inclusion.
"Homosexuality is a disordered behaviour. The activity must be condemned," he insisted, expressing sadness that dialogue between the Anglican communion and the Roman Catholic church had been seriously compromised over women's ordination and homosexuality. Kasper later triggered protests after criticising England's multiculturalism.
Meanwhile numerous Roman Catholic theologians, priests and laypeople in Britain and beyond were distancing themselves from the Vatican's stance on women and gay people and failure adequately to tackle child abuse.
What would improve inter-church relations at international level might damage them at the grassroots, where ordinary Christians befriend one another and join in projects such as night shelters for homeless people.
Despite the pope's rather tactless wooing of Church of England opponents of women's ordination, cordial relations continued.
Williams occasionally expressed polite disagreement with the hardline stance and authoritarianism of other churches.
Nevertheless he went on trying (with limited success) to reshape the communion to make it more palatable to the Roman Catholic and Eastern Orthodox hierarchies as well as member churches intent on imposing their views on others.
This included arguing that same-sex unions should not be blessed without the agreement of ecumenical partners. He has also sought to dilute proposals to allow women bishops in the Church of England.
Russian Orthodox leaders have been criticised for their closeness to an authoritarian state, and have backed anti-gay laws that undermine basic freedoms.
In 2012, Hilarion called for an international Orthodox and Catholic alliance to defend "traditional Christian values" including "the possibility of marital union as a union only between man and woman".
Papal representative Archbishop Antonio Mennini, visiting Britain, urged cooperation with other faiths as well as denominations to oppose same-sex marriage.
Perhaps Church of England members, and other Anglicans, should discuss how far the quest for truth, love and justice, and local mission, should be compromised in attempts to win the favour of Vatican and Eastern Orthodox leaders, who no doubt will continue to disapprove of Anglicanism.
Their views should be taken seriously, but unity is not the same as conformity.