The gathering, in Canterbury, is expected to last a week, with many suggesting that conservative bishops from Africa and Asia may stage a walk-out, unless clerics from the more liberal nations rein in their support for gay marriage.
The letter, whose signatories include eight retired bishops and seven archdeacons, calls on the Church to acknowledge that gay members have been treated as “second-class citizens”.
It tells the two archbishops that the Anglican Church should “apologise for our part in perpetuating rather than challenging ill-informed beliefs”.
It adds: "We have not loved them as we should, and have treated them as a problem to be solved rather than as brothers and sisters in Christ to be embraced and celebrated. We have made them feel second-class citizens in the Kingdom of God, often abandoned and alone.
"We, the Church, need to apologise for our part in perpetuating rather than challenging ill-informed beliefs about LGBTI people, such as the slanderous view that homosexuals have a predisposition to prey on the young."
The letter was put together by Jayne Ozanne, director of the Accepting Evangelicals group, which campaigns for the rights of gay, bisexual and transgender Christians.
She told the BBC a "line" had been reached, adding: "It was time to stand tall and actually call the Church back to its roots to reminding them about the fact that we are there to welcome and serve all.”
Source: http://telegraph.feedsportal.com/c/32726/f/579309/s/4cc1a31c/sc/13/l/0L0Stelegraph0O0Cnews0Creligion0C120A915650CChurch0Emust0Erepent0Efor0Etreating0Egays0Elike0Esecond0Eclass0Ecitizens0Bhtml/story01.htm