I feel like this is an issue that philosophers should have bickered over for a few centuries by now, so I'm disappointed that I cannot easily find a summary of the arguments against sacred symbols. I recall the essay "against moralism", but it's not addressing this exact point. There are also plenty of arguments against nationalism, which is just one context for sacred symbols. Who has made the general argument against sacred symbols?
The best I could find was an essay called "Is nothing Sacred" attributed to Salman Rushdie, in which he defends the value of the novel. There is one paragraph that gets to the point:
No, nothing is sacred in and of itself.... Ideas, texts, even people can be made sacred - the word is from the Latin sacrare, "to set apart as holy" - but even though such entities, once their sacredness is established, seek to proclaim and to preserve their own absoluteness, their inviolability, the act of making sacred is in truth an event in history. It is the product of the many and complex pressures of the time in which the act occurs. And events in history must always be subject to questioning, deconstruction, even to declarations of their obsolescence. To revere the sacred unquestioningly is to be paralyzed by it. The idea of the sacred is quite simply one of the most conservative notions in any culture, because it seeks to turn other ideas Uncertainty, Progress, Change - into crimes.That's a good start. Of course, it's detached from the arguments for sacredness, so it has limited value. But it's enough to demonstrate that respect for the sacred is not a self-evident good.