Its formation coincides with the launch of the Silent No More report documenting the role of the church in response to sexual violence in the Democratic Republic of Congo, Rwanda and Liberia.
The report was launched today at Lambeth Palace, the official residence of the Archbishop of Canterbury, as the coalition's first step towards addressing the silence, pain and stigma faced by survivors of sexual violence.
Speaking at the launch, Dr Williams said: "It is of the first importance that churches and all communities of faith continue to hold before the world's eyes the absolute priority for justice and dignity for all.
"We need to equip people to become agents of change and agents of hope.
"I hope this is the beginning of the church being what it ought to be and should be."
UN statistics on sexual violence paint a harrowing picture. Worldwide, one in five women will become a victim of rape or attempted rape in her lifetime.
The launch was joined by the Archbishop of the Democratic Republic of Congo, the Most Rev Henri Isingoma. In the DRC, rape has been used as a weapon of war in the conflict in South Kivu between the government and rebels connected to the 1994 Rwandan genocide.
According to UN humanitarian news agency IRIN, around 8,000 rapes were recorded in South Kivu in 2010. Since the start of 2011, charity Medecins sans Frontiers says it has treated more than 200 women, men and children for rape in the region.
Michel Sidibe, executive director of UNAIDS, said the organisation wanted to work closely with faith-based organisations to ensure the dignity and protection of women and girls, who account for the largest proportion of the victims of sexual violence.
Lyn Lusi, co-founder of Tearfund partner HEAL Africa, said the church must follow the example of anti-slave trade campaigner William Wilberforce in pursuing justice for men and women.
She said: "Attitudes to women need to change if a woman's lot is to get better. It's about partnership as God intended, and understanding one another's roles. The church needs to be a model for this partnership."
People are being asked to show their support by signing the Silent No More pledge at wewillspeakout.org