I think that some people are failing to realize the meaning of a symbol. A symbol is more than just a visual sign, like a poster or card, but something that represents or stands for another object, idea, person or concept. It is 100% correct to say that a rock is a symbol for God, for in a figurative sense “rock” describes the qualities of God as the Father of Israel (De 32:18), as a stronghold (2Sa 22:32, 33; Isa 17:10), as the secure height and refuge of his people (Ps 62:7; 94:22), and as their salvation (De 32:15; Ps 95:1). Some have looked to false gods as their “rock.” (De 32:37) There are other examples in which “rock” symbolizes in a general way a place of safety, protection, security, and refuge. (Isa 2:10, 19, 21) In Isaiah 8:14 Christ Jesus is alluded to as “a rock” over which “both the houses of Israel” stumbled.--Mt 21:42-44.
In Bible symbology the sea is used to picture “peoples and crowds and nations and tongues,” the vast body of mankind that cover the habitable earth as the waters cover the sea basins. They are all the people alienated from God by sin and by the “ruler of the authority of the air,” Satan the Devil. (Rev. 17:15; Isa. 57:20, 21; Eph. 2:2)
Certain major world powers of history appear directly in the Biblical record, and all of these, as well as other nations, have used animals as symbols of their governments. . In Egypt, the serpent figured prominently, the uraeus, the sacred asp, appearing on the headdress of the Pharaohs. However, Egypt was also represented by the bull, as was Assyria. Medo-Persia used the eagle (the shields of the Medes bore the golden eagle; the Persians bore an eagle fixed to the end of a lance). Athens was designated by the owl; Rome, the eagle; Great Britain is designated by the lion; the United States, the eagle. From the most remote times China has been symbolized by the dragon. Well known are the Russian “bear” and the German “two-headed eagle.”
Symbols and analogies aren't useless to describe God because it helps our minds wrap around a concept that is bigger than any of us can ever know. Tools like personification give scope to things we normally wouldn't understand, or even dare to try to understand due to its complexity. Representations, signs or symbols bring things down to our level. Even though these representations seldom live up to fully describing all aspects of what they are representing, they still give us a little insight on the matter. Symbols are all around us everyday. It's become a central part of our normal lives to the extent that we sometimes use them without even realizing it. Since they are so common, why shouldn't we use them to better understand the ways of God? Even if they fall short of defining God in His entirety (after all, who can truly describe every facet of the Almighty?) it can still draw us one step closer to His being, and it is probably one step that we could never have fully appreciated without the use of symbols.