This manoevre, turning an insult into a badge worn with pride is a sign of a confident and assured movement. To shift focus a little, in the 1990s, opposition fans at Old Trafford used to mock the home fans' rendition of 'Glory, Glory, Man United' with their own version: "Who the f*** are Man United?" today, after years of triumph and success, United fans themselves sing the latter version with gusto, turning everything on its head. In the 1950s and 60s the word 'black' was considered to be an insult to what were at the time called 'coloured' people. in the C20th, Homosexuals turned the originally insulting words 'gay' or 'queer' into titles of pride. Even the word 'Christian' was originally coined as a Latinism by the very Roman authorities in Antioch that sought to suppress the new superstition that was arising in the city, which then became adopted as a self-chosen designation by the movement.
The use of the cross by Christians is exactly that kind of confident ironic paradox - the turning of a badge of shame into a sign of identity. It isn't a sign of Constantinian political religion, as Giles Fraser fears, or a defiant stand made by beleaguered Christians in a secular culture, but a touch of self-mocking irony - a sign of the overturning of values that happens in the kingdom of God, which is why Christians should wear it with pride. And a smile.