Justin Welby will tell worshippers at Canterbury Cathedral that darkness is a "monster that lies" as he refers to the terrorist atrocity which killed 25-year-old Jack Merritt and 23-year-old Saskia Jones.
During his address, the archbishop is also expected to speak of a recent visit to Beni, in the Democratic Republic of Congo, which has had an outbreak of the Ebola virus.
He will deliver his sermon during a Eucharist service at 11am on Christmas Day.
"Canterbury - a place of some 50,000 people, is a city of peace celebrating Christmas," he is expected to tell the congregation.
"Now imagine a city five times this size where its citizens face disease and war this December 25. I was there in October. It is called Beni.
"It has been at the centre of the second worst outbreak of Ebola; about three thousand people have died. Its Anglican bishop is alight with Christ, always present, always giving of himself.
"Darkness is a monster that lies. Its growling claims seem to call out with a louder volume than the love filled whispers of the light. "We see the shadows out of the corner of our eyes. They may be violence as in the Congo or on London Bridge."
He is due to add: "Whether solid or illusion, they are the reality with which we live, if we believe the dark."
While discussing darkness and light, the archbishop, leader of the Church of England, is also due to tell the cathedral in Kent that "the closer we get to the light the more our imperfections are revealed”