We want to fight ferociously against the fanatical, unconscious and snobbish religion of the past, which is nourished by the evil influence of museums. We rebel against the supine admiration of old canvases, old statues and old objects, and against the enthusiasm for all that is worm-eaten, dirty and corroded by time; we believe that the common contempt for everything young, new and palpitating with life is unjust and criminal.
Source, in full
Sometimes attributed to Marinetti as on this page, the quote is actually from the "Manifesto of Futurist Painters" (11 February 1910) whose primary author was Umberto Boccioni, with additional contributions from Giacomo Balla, Carlo Carrà, Luigi Russolo, and Gino Severini. The quote can be found on p. 434 of Artists on Art (1945) translated as "We want to fight relentlessly against the fanatical, irresponsible, and snobbish religion of the past, which is nourished by the baleful existence of museums. We rebel against the groveling admiration for old canvases, old statues, old objects, and against the enthusiasm for everything moth-eaten, dirty, time-worn, and we regard as unjust and criminal the usual disdain for everything young, new, and pulsating with life"