Father John-Francis Friendship, who is in a civil partnership, wrote that Dr Wiliams' comments on gays did "immense harm" to the gospel and criticised his use of the word "lifestyle".
He told PinkNews.co.uk that he could not see why a gay person would want to join the church right now.
The open letter was written as a response to a statement from Dr Williams following a decision by US Anglicans to ordain gay clergy…
… He wrote: "We do not believe that your ‘Reflections’ speak to the needs of our own culture or society. In particular we believe your references to civil partnerships as a “chosen life-style” and your assertion that those who have made such a commitment are in the same position as “a heterosexual person living in a sexual relationship outside the marriage bond” do immense harm to the gospel.
"Whilst we applaud your desire that we are called to “become the Church God wants us to be, for the better proclamation of the liberating gospel of Jesus Christ” we find no indication of how that can be for those who are not heterosexual, nor any indication of what that liberating gospel might be."