The Archbishop of Canterbury called on Christians and others to reaffirm "solidarity" with each other and to affirm the "treasures of freedom". He was speaking after a blitz of terror attacks around the world including Tunisia, France and Kuwait.
At least 27 people have been brutally murdered by terrorists while sunbathing at two hotels popular with British and Irish tourists in Tunisia.
The hotels where the attacks took place are in Sousse in the Kantaoui area, on the Mediterranean. The latest attacks in the former French colony follow the Islamic State murders in March of 20 people at an art museum in Tunis.
According to reports coming out of the interior ministry and other sources in Tunisia, the terrorists used guns and a grenade. Photographs showed blood spattered tourists lying dead beside sunbeds appeared on Instagram. The Foreign and Commonwealth Office in London gave hotline number of 0207 208 1500. There are understood to be a lot of tourists from Ireland in the city this week, although Dublin's foreign affairs department said there were no reports that any Irish citizens had been hurt or killed.
Thomas Cook, which operates flights from Gatwick to one of the hotels, the Marhaba, said in a statement: "Thomas Cook has been advised of an incident that occurred earlier today in Sousse, Tunisia. At this time, details are not clear as to which properties have been affected, with conflicting news reports. We are currently gathering information and will provide an update as soon as possible. Our teams on the ground are offering every support to our customers and their families in the area.
"We will continue to monitor the situation, working closely with the FCO and local authorities."
One onlooker in Tunisia tweeted: "Explosion in a hotel & a Gunman armed with a machine gun shot at groups of tourists lying on sunbeds."
Another person in the area tweeted: "Oh god, I heard gunshots and I am feeling scared. #sousseattack. And I heard that there's gunman in Tunisia, Sousse."
The interior ministry said one gunman with a Kalashnikov had been shot dead and police were in pursuit of another.
Tunisia has been on high alert since March's attack on the Bardo museum in Tunis, killing a group of foreign tourists.
Since its 2011 uprising to oust autocrat Zine el-Abidine Ben Ali, Tunisia has been praised for its peaceful democratic transition. But it has also seen the rise of hardline conservative Islamist movements.
Several thousand Tunisian jihadists have left to fight in Syria, Iraq and neighbouring Libya, where some have set up jihadist training camps and promised to return to attack their homeland.
Archbishop Justin Welby said: "All of us must be full of grief at the attacks in Tunisia, France and Kuwait. They are intended not only to destroy but to divide, not only to terrify but to take from us our own commitment to each other in our societies. Let us together mourn for the victims, weep with the bereaved, support the injured and pray for them all to the God who in Jesus Christ went to the Cross and died rather than bearing a sword.
"Facing such a global and long term menace, we are called to reaffirm our solidarity with each other and affirm the great treasures of freedom, in religion and so many other ways. Our strength is in the God who conquered evil when Jesus rose from the dead, and on His death and victory we find the basis for our future. "
Additional reporting from Reuters.
