Gene Robinson and I were sitting in a pub just behind St Paul's Cathedral a few months ago. He drank lime and soda. I had something stronger. "You drink the first drink, then the next drink drinks you," he warned me. Ever the evangelical of his past, Robinson's concern for my drinking was rooted in bitter experience.

For him the booze had been just one of the temptations in dealing with the bucketloads of hate that have been poured over him since he became bishop of New Hampshire in 2004. Being the first openly gay bishop in the Anglican Communion has, as he put it, "taken its toll". His announcement this weekend that he is retiring as the bishop of New Hampshire in a few years' time can come as little surprise.

There are many gay men and women in the church serving as priests and bishops, but as the focus of such international attention, he has had it toughest of all: the death threats, the abusive letters and phone calls, the heckling during sermons, the constant pressure to justify himself and his faith. At the last international gathering of all the world's bishops, the Lambeth Conference, he was barred by the archbishop of Canterbury. A lesser man would not have been able to cope, nor do so with such gentleness and grace.

There is no doubt in my mind that Robinson has been a prophet in the Anglican communion, recalling the church to its best instincts of inclusion and commitment to those who are excluded and marginalised. In Christ there is neither Jew nor Greek, rich nor poor, black nor white, gay nor straight. Some day this will be as obvious to the church as the fact that slavery is evil. But the forces of reaction remain strong and are getting stronger.

The latest thinking within the church to exclude new Gene Robinsons is called the covenant, due to be discussed at General Synod this month. The idea is that conservative anti-gay provinces – places like Uganda and Nigeria where Anglicanism is numerically on the up – will have a legal mechanism to stop more progressive churches from following the Gospel as they understand it.

In a particularly nasty twist of the culture wars that are developing around this issue, the architect of the covenant, the Right Rev Gregory Cameron, bishop of St Asaph in Wales, has accused those who are against the covenant of racism. Those, like me, who fear the homophobia that is prevalent in many parts of the world are attacked as "little Englanders". At the time of writing, a Church Times online survey asking "Should the church reject the Anglican covenant?" shows 84% saying that we should.

The Church of England – and by that I mean the ordinary man and woman in the pew – is considerably more progressive, on women bishops and gay marriage, than its conservative and often overly fearful leadership. Churchgoers know that the time for change is overdue. And many have come to see this because of the inspiring and compassionate faith of people like Robinson.

For too long Christianity has lent the bigotry of homophobia a cloak of respectability. Robinson is, of course, quite right to shout loudly about those "tragic stories of teenagers who have taken their own lives because religion tells them they are an abomination before God, and who believe their lives are doomed to despair and unhappiness". These days the alibi for this sort of prejudice is called unity – that we mustn't do anything that might upset our conservative brothers and sisters. Indeed, had the covenant existed in the era of the prophets of the Hebrew scriptures, it would have provided a perfect way of muzzling them too.