Coptic Orthodox Archbishop Angaelos and Archbishop of Canterbury were among the Church leaders and politicians remembering the 21 Christians martyred in Libya six years on from their death.
The men, Coptic Orthodox Christians, were murdered by ISIS on a beach in Libya on 15 February 2015. They were all from Egypt, with the exception of Matthew Ayariga from Ghana, and were in Libya as construction workers when they were kidnapped from Sirte.
Footage of their executions was released on video, shocking the world but also moving many with their bravery.
They are remembered on Contemporary Martyrs Day, held each year in their memory by the Coptic Orthodox Church on 15 February.
Commemorations were held online this year because of Covid-19.
Coptic Orthodox Archbishop of London, Archbishop Angaelos, said: "What we are talking about here is not an attack on the Coptic Orthodox Church, or Coptic Orthodox Christians, because there is no monopoly of suffering or persecution.
"For to persecute is to dehumanise, to commodify, to take away the image and likeness of God that is within and that is at the core of our humanity.
"Through the witness of the 21 we have learned resilience, we have learned generosity, we have learned graciousness, we have learned to love quite literally those who seek to kill us, and we have learned to forgive, and so we are thankful for their witness.
"As Christians this is our calling, who we are, we would not be true to ourselves if we do not advocate and stand together for people of all faiths and none, because we all share that humanity ... when we stand against oppression and against persecution, we gain, because our humanity is enriched."
Pope of Alexandria, Tawadros II, spoke of his hope for a time when there is no more persecution in the world.
"It is true that we are proud of the faith of all martyrs, who can face death with courage to witness to their faith, yet we cannot by any means tolerate persecution, a word that should be wiped out of the dictionary of humanity," he said.
"We also have great faith in the value of human life, which is a gift from God and no man has the right to end human life by any means.
"It is well understood by all Christians that witnessing our Faith in the Lord Jesus Christ is joyful, even if it is through giving our life. That is why we today celebrate the commemoration of our beloved martyrs of Libya, and all martyrs of faith with complete understanding of the verse 'For me to live is Christ, and to die is gain' (Philippians 1:21)."
Church leaders also remembered Christians and people of other faiths who continue to experience persecution today, including Uighur Muslims in China and Rohingya Muslim communities in Myanmar.
Lord Alton of Liverpool paid tribute to Ayariga, whose remains were taken to Egypt just last year so that he could be buried alongside his Egyptian brothers.
Lord Alton said there was too much "indifference" towards the estimated 250 million persecuted Christians worldwide, and blamed the "tepid response" on "political expediency, institutional considerations, or trade and business".
"The Coptic tradition of Christianity has so much to teach us – not least their experience and understanding of endless centuries of discrimination, persecution, and martyrdom," he said.
"Heroic bravery in the face of evil demands a better response from us – even if it is only a pale imitation of the remarkable act of solidarity by Matthew Ayariga on that deadly beach in Libya in 2015."