With their heads bowed, they trudge one behind the other in a long line through wet sand.

They are wearing orange overalls, their hands are lashed behind their backs.

Every step brings you closer to certain death.

Because IS fighters in black hoods lead them, 21 Coptic Christians, across the beach in the Libyan city of Sirte to an execution.

The video recordings of this march went around the world in February 2015.

Since then they have been symbolic of the persecution of Christians in Muslim countries.

Islamism has plagued the Middle East and North Africa for more than 20 years. An unprecedented wave of terror in many countries, it is primarily directed against religious minorities. Especially against Christians. An overview of the countries where Christians live most dangerously shows how much the threat situation has worsened.