Story highlights Within hours, bigots were using the attack for their own political gain, Hellyer writers

Racists must be told in no uncertain terms that our society is for all of us, he writes

H.A. Hellyer, senior nonresident fellow at the Atlantic Council and the Royal United Services Institute in London, is author of "Muslims of Europe: The 'Other' Europeans" and "A Revolution Undone: Egypt's Road Beyond Revolt." He is on Twitter @hahellyer. The opinions in this article belong to the author.

(CNN) I remember well the attacks London suffered on July 7, 2005. I remember the shock, the anger and the outrage. I remember the fear, the concern and the trepidation. And I also remember the courage, the persistence and the perseverance.

I served as deputy convenor of the Her Majesty's Government's working group on tackling radicalization and extremism, set up in the wake of that grotesque attack.

In the aftermath of Wednesday's terrorist attack in Westminster, I am reminded of the lessons from 2005: both how to respond and how not to respond; how to stand united and how not to allow the vile attackers to claim any real victory.

It was only a matter of hours before some bigots decided to use this despicable attack on one of our most enduring symbols, the Palace of Westminster, for their own base political purposes.