One of the very first symbols that meets the candidate on a conscious level during his or her admission into the Order of the Golden Dawn (in the Outer) is the Red Cross surmounted over a White Triangle, positioned upon the black double cubical altar. Being blindfolded the candidate places his or her hand upon this highly significant symbol during the obligation of the Neophyte. Some moments later, during the circumambulations and purifications of the candidate, he or she meets this symbol again but now with the Red Cross placed inside the White Triangle as born upon the Banner of the West. In either case this symbolism of the Red Calvary Cross and the White Triangle is emblematic of the Outer Order, or the First Order called the “Golden Dawn”. […]

Source:   Cross symbolism in the Golden Dawn