Pride - the worst sin according to C.S.Lewis

[Belacqua]

I think that's potentially a good description of pride—a standard people believe they deserve to have relative to others. And a big part of Christianity has to do with doing away with such standards. To be willing to cross group boundaries, especially ones you feel are beneath you. I remember someone saying once (maybe it was CS Lewis himself), that the most powerful image in Christianity wasn't the cross, but Jesus washing the feet of the disciples.

Yes, I think this is exactly what Christians mean when they say pride is a sin. 

To refrain from demanding special treatment, and to value even those whom we could easily judge to be inferior.