Gene Robinson, Bishop of New Hampshire, spoke at the 10th anniversary celebration of Changing Attitude, a gay rights group.
The BBC reports Robinson called the Catholic church's refusal to ordain gay men "vile" and said the current prejudice against gays will lead to more members leaving the church.
Robinson said the church hierachy is addressing the pedophile scandal the wrong way.
He said they are blaming homosexuals specifically for it instead of child abusers in general.
His speech at St-Martin-in-the-Fields church in Trafalgar Square caused a controversy. Robinson was asked not to wear full vestments or be in the service before his speech.
The Archbishop of Canterbury was urged by the London Diocesan Evangelical Fellowship to move the speech to a secular venue.
Robinson predicted that one day homosexuals wouldn't be discriminated against by the church.