The Archbishop of Canterbury has called the Church of England "deeply institutionally racist" and apologised for Britain's treatment of black people and other minorities since World War II.
Anglican clerics adopted a motion late on Tuesday seeking forgiveness from the so-called Windrush generation that moved to Britain from former Caribbean colonies since 1948.
The mass migration was promoted by the government to help rebuild the United Kingdom from the ruins of war.
Yet none received documents confirming their UK citizenship and the Caribbean countries' subsequent independence saw many denied basic rights.
Dozens were also wrongly deported in a scandal that rocked the government of former prime minister Theresa May.
Archbishop of Canterbury Justin Welby, the highest-ranking cleric in the Anglican communion, told the General Synod there was "no doubt" the Church of England was still "deeply institutionally racist".
"We did not do justice in the past, we do not do justice now, and unless we are radical and decisive in this area in the future, we will still be having this conversation in 20 years' time," the archbishop said.
"We have damaged the Church, we have damaged the image of God and most of all, we have damaged those we victimised."