To any Westerners reading this thread, this will be your fate soon. The attack near Parliament and that at the Ariana Grande concert aren't even a half year apart. The interval between these attack would become shorter as you get more radicals coming home from Iraq and Syria.
This is our faith now. When the first of these outrageous attacks hit major Western European cities like Charlie Hebdo in Paris I thought to myself "OK, this is the time when we finally wake up and stop this from happening in the future"
Fast forward a few years to the present moment, terrorist attacks are becoming a daily thing and people and governments seem to care less and less and get used to it. We even get to idiotisms like the mayor of London saying that these attacks are "part and parcel of living in a big city"