1. Signs and Symbols

4. The difference between Symbols and Signs - 1
“Symbols have one characteristic in common with signs; they point beyond themselves to something else. The red sign at the street corner points to the order to stop the movements of cars at certain intervals. A red light and the stopping of cars have essentially no relation to each other, but conventionally they are united as long as the convention lasts.”

5. The difference between Symbols and Signs - 2
“The same is true of letters and numbers and partly even words. They point beyond themselves to sounds and meanings. They are given this special function by convention within a nation or by international conventions, as mathematical signs. Sometimes such signs are called symbols; but this is unfortunate because it makes the distinction between signs and symbols more difficult. Decisive is the fact that signs do not participate in the reality of that to which they point, while symbols do. Therefore, signs can be replaced for reasons of expediency or convention, while symbols cannot.”

6. Signs as Arbitrary Signifiers
So, when we talk of the relationship of energy and matter we say E=MC2.
This is ‘sign language’. There is no reason why we should not say X=YZ2.
This is because we are talking the language of maths and physics where the sign is identified with that to which it points.
However, when we talk of God we are dealing with an:
"…area of human awareness and communication where what we think and what we say can never be perfectly clear." 
We are in the area of symbol.

7. Symbols are Ambiguous
This ambiguity of symbols, - their inability to precisely identify something- is a frustration to our culture which is still strongly infected with the excessive rationalism of the logical positivists. But the ambiguity and imprecision of symbols is their strength for Tillich.

8. Ambiguity
"They open up levels of reality which otherwise are hidden and cannot be grasped in any other way."

9. For Tillich Symbols do several things:
Point beyond themselves to something else.
Participate in the reality to which they point.
Open up levels of reality which are otherwise closed to us.
Unlock dimensions and elements of our soul which correspond to the dimensions and elements of reality.
Crucially symbols actually make present what they represent, and that in a transformative way, because they participate in the reality to which they point.
That is why Tillich says,
“One should never say ‘only a symbol’, but one should say, ‘not less than a symbol’.”
This is because symbols are what they are but are also, in a way more than what they are.
To understand this we need to go back to the distinction between signs and symbols.

10. Signs are arbitrary signifiers, pointing beyond themselves toward something else, but having no essential or necessary relationship to their referents. A written word is an outstanding example of the purely arbitrary connection between a sign (the word on the page) and its referent (the sound-image and concept to which the written word points).
We know to think of edible things when we see the word "food," but the four letters in that word have no necessary relationship with the sound-image of that word in spoken language, nor do they have a necessary relationship with the concept of edible things.
Even less does the written word "food" hold a necessary relationship to actual edible things. Only through a process of association and social convention has this written sign come to signify the sound-image, concept, and objects to which the word points.

11. A symbol, like a sign, points to something beyond the symbol itself
A symbol, like a sign, points to something beyond the symbol itself. Unlike a sign, however, which is only arbitrarily linked to its referent, a symbol "participates in the reality" to which it points.
Through their liturgical use, the written words of 1 Corinthians 23-25…
"Take, eat: this is my body which is broken for you. This do in remembrance of me"
…have ceased to be merely signs.
The Eucharistic meal is an example of a religious symbol. The bread and wine are not incidental to the symbol's power, but integral to it. Liturgical and sacramental activity and language do not simply signify their meanings; they participate in their meanings.

12. How the Eucharist works as Symbol
The meaning of the Eucharist could not be conveyed with the replacement of the bread and wine by other "signs," because the meaning of the action actually depends on their specific qualities as symbols. In fact, it seems that one of the crucial distinctions between a sign and a symbol is that the referent (or object) of a symbol cannot be perceived separately to the symbol, whereas the referent of a sign is independent of the sign assigned to it.

13. God as Symbol
Tillich views God as the greatest of religious symbols, but also says that it is inappropriate to "simply say that God is a symbol."
There are two crucial aspects of the nature of the symbol of God: a transcendent aspect and an immanent aspect.
First, the symbol "God" conveys above all else transcendence.
The First Commandment introduces God's transcendence in mythic language: "Thou shalt have no other gods before me"; Anselm uses the language of Greek philosophy: "God is that than which nothing greater can be imagined."
In each case, the definitions point to something real that transcends everything; including statements made about that reality.
The referent of "God" is transcendence.

14. But it’s not quite that simple…!
In terms of its referent, however, the symbol "God" must be seen to include a non-symbolic element, for God's transcendence is not merely symbolic but real.
It is, however, the immanent aspect of the symbol "God" that allows the symbol to convey the transcendence to which the symbol points and in which it participates.

15. Understanding God as Symbol
Symbols, by their nature, emerge from our experience of the world, but our experience is not transcendent but specific. We cannot, in other words, simply have an experience of God’s transcendent nature, which Tillich calls Being-in-Itself.
The symbol "God" combines a transcendent and an immanent aspect, for the qualities that make God thinkable are taken from experienced qualities we have ourselves. These qualities are immediately recognizable as symbolic when we realize that they convey the ultimacy or transcendence of God even though no one of them can be literally applied to God.

16. Understanding God as Symbol cont…
Without the qualities, however, the transcendence of God would be incomprehensible – he has to have some qualities we are familiar with or we would have no idea what he is like.
The symbolization of God is a human activity apparent in religious devotion and theological reflection. The immanent nature of the symbol provides us with characteristics of God, but those characteristics point us toward the transcendence that is God. Without the immanence of the symbol, however, we could never be pointed toward transcendence. This is why religious symbols not only point to but also participate in the reality to which they point.

17. The Most Perfect Symbol
If God, as Symbol, needs to contain both an immanent aspect (for our understanding) and a transcendent aspect (to point to something greater) then the Bible offers us one example of a perfectly symbolic God.
This is Jesus, who, through being incarnates is made Immanent yet, though his resurrection and ascension is also Transcendent.

18. Jesus in other Philosophy
It is of interest to note that this fits very well in to the philosophies of GWF Hegel and Immanuel Kant.
Both Kant and Hegel believe there is a realm of knowledge to which we either can never, or would struggle to access. This is the world of the Noumenal/The Spirit.
Jesus comes ‘from’ this world and makes it present in the world of the Phenomenal/Illusion.

19. Some final thoughts
Tillich’s point, really, is that religious talk is often symbolic – it is what it is but it also points to something great. Whilst we may be able to critique it as a sign – as Ayer, and the Logical Positivists would try and do – we can’t critique what it points to or reveals. This extra dimension is what the Logical Positivists were missing and it is in this way that we can successfully talk of God.