Church leaders and Christian groups have called on the Government to do more to prevent genocide worldwide.
In a letter to mark Holocaust Memorial Day, they accused the UK and other countries of ignoring the "warning signs" of genocide and continuing to "look the other way" out of diplomatic and economic self-interest.
Mass atrocities against Christians in Nigeria by Boko Haram and Fulani militia, and by the Chinese Communist Party against the Uyghurs were two instances that meet the legal definition of genocide, they said.
"After the egregious Nazi crimes, states have been promising to never again allow such mass atrocities to be perpetrated," the letter reads.
"However, time and time again, the international community has failed to deliver on its solemn promise. This failure is, in large part, because the states themselves, including the UK, are not effectively fulfilling their duties under the UN Convention on the Prevention and Punishment of the Crime of Genocide (the Genocide Convention).
"Again and again, we are failing to act to prevent genocide, doing little to suppress it, failing to give the full support needed to those affected and shying away from prosecuting perpetrators."
The letter has been signed by the Coptic Orthodox Archbishop of London, Archbishop Angaelos, the Bishop of Truro, Philip Mounstephen, who oversaw the Government's recent review into persecution, and Christian charities Open Doors and Christian Solidarity Worldwide.
"Actions speak louder than words," they said.
"The lack of action means that those conducting the crime still believe they can act with impunity. Impunity begets further crime.
"If we do not stand up now, this will be the legacy that we leave for future generations who will only see more and more such atrocities."
They said they were "profoundly concerned" that the Government had chosen not to support an amendment to the Trade Bill that would have required it to reconsider trade deals with countries where genocide is taking place.
They said this sent the "wrong message" to states involved in such atrocities.
"As the UK has left the EU this is the perfect time for us to redefine ourselves and affirm our moral position globally," the letter concludes.
"We need your vision for genocide prevention. No empty promises. We need your leadership on the issue of genocide responses. No excuses.
"Informed responses to genocide start with recognising the issue, recognising the risk of genocide or of genocide being perpetrated. No empty promises. No excuses."