Dr Rowan Williams said the decision by the Episcopal Church to ordain a partnered homosexual bishop had had a "devastating" impact on the freedom of Anglicans elsewhere to proclaim the Gospel, while the freedom of Anglicans in Uganda to support anti-gay legislation had had a "serious impact on the credibility of the Gospel" in other parts of the Anglican Communion.
In an appeal for unity, he said: "The challenges of our local and global Anglican crises have to do with how this shapes our councils and decision-making. It is not a simple plea for the sacrifice of the minority to the majority. But it does mean repeatedly asking how the liberty secured for me or for those like me will actively serve the sanctification of the rest."
He called for a "major change of heart all round" among Anglicans and urged them to "discover an ecclesial fellowship in which we trust each other to act for our good". Without these, he said the prospect of a two-tier Anglican Communion would be likely.
The Archbishop said Anglicans had to make difficult judgements about whether granting freedom to one group would be more likely to undermine the other's freedom and whether or not granting a particular freedom would "set free the possibility of contributing to each other's holiness".
"We may be able to show to the world a face rather different from the anxious, self-protective image that is so much in danger of entrenching itself in the popular mind as the typical Christian position," he said.
"I deeply believe that this Church and this Synod is still capable of showing that face and pray that God will reveal such a vision in us and for us."
The Archbishop said an anti-homosexuality Bill was "repugnant", as the head of the Anglican Church of Uganda, Archbishop Henry Orombi, issued a statement affirming the Ugandan Church's support for the Bill.
The Archbishop was speaking in his presidential address to the Church of England General Synod today. His speech has been hailed as one of the best in years by Synod members.
Dr Williams also warned that legalising assisted suicide would be a "moral mistake" that would take Britain into "very dangerous territory".
His comments come just weeks before the Director of Public Prosecutions Keir Starmer QC is due to issue finalised guidelines on the circumstances in which someone may be charged for assisting another person in taking their own life.
Although under current law assisting a suicide is a crime punishable by up to 14 years in prison, recent high profile court rulings have thrown the law on so-called "mercy killings" into confusion.
Dr Williams told Synod: "The Church does not assume that it has the right to impose any solution but it will argue fiercely, so long as legal argument continues, that granting a 'right to die' is not only a moral mistake, as I believe myself, but the upsetting of a balance of freedoms.
"The balance of liberties still comes out against a new legal framework, and in favour of holding to the principle – not that life should be prolonged at all costs, but that the legal initiating of a process whose sole or main purpose is to end life is again to cross a moral boundary, and to enter some very dangerous territory in practical terms."
He expressed concern for the vulnerable in society, stating that they may come to feel manipulated, harassed or demoralised.
Any change to the law, he added, would result in the "worthwhileness" of some lives being "undermined by the legal expression of what feels like public impatience with protracted dying and 'unproductive' lives".
The DPP was asked to draw up guidelines on the legal position on assisted suicide after the House of Lords backed an appeal from multiple sclerosis sufferer Debbie Purdy for clarification on the law.
It is the first time the Archbishop has commented publicly on assisted suicide since the DPP indicated last September that those who help another person to end their lives on compassionate grounds are unlikely to face prosecution.
The debate on assisted suicide resurfaced last month when Frances Inglis was sentenced to nine years for murdering her 22-year-old son, Thomas, who suffered from brain damage, a week before a court acquitted Kay Gilderdale of the attempted murder of her 21-year-old daughter, Lynn, a chronic ME sufferer.