The basis for types, or typology, is the Greek word tupos, which occurs 16 times in the New Testament. Tupos is variously translated as: print (of the nails), figure, fashion, manner, form, example or pattern. This Greek word means, variously, “a mark made as a result of a blow or pressure, mark, trace”, “copy, image”, “form, figure, pattern”, “type, pattern, model”, “text, context” [1].
In the context of typology, a type might best be defined as a prophecy not in words but in a person, object or event.
Each type has an antitype, the thing that the type is pointing towards. So, for example, the print of the nails (John 20:25) have as an antitype the nails, the thing to which the prints correspond. Only one thing will properly fit the pattern that is the type.
Often types are related to their antitype in one specific aspect. For example, in Romans 5 Adam is a type of Christ. The way he is a type of the Lord Jesus is in his headship over the human race. By his action sin came into the world, affecting all who would come after him for whom he is head. Similarly, the Lord Jesus is the head of those who turn to Him for salvation, bringing life rather than death. Adam is not a type of Christ in his failure and sin, for the Lord Jesus didn’t sin or fail. Therefore, a type must be restricted to specific aspects of the person, object or event.
Note that being a type does not change the historicity of the person, object or event. The historical reality of the person, object or event doesn’t change, even though there was a second, prophetic meaning that God was revealing. This differs from spiritual interpretation, which discounts the historical or primary meaning in favour of the perceived spiritual meaning.
What can be a type? Provided is a very small, non-exhaustive list:
1. Adam as head, Romans 5
2. Melchizedek as priest, Hebrews 5-7
3. The serpent on the pole, John 3:14
4. The Passover lamb, 1 Corinthians 5:7
5. The Exodus, Matthew 2:15
There are many other types in the scriptures. There are different ideas regarding how many types there are, or what can be a type. On one end of the spectrum are those who believe that anything can be a type. On the other end of the spectrum are those who believe that types must be clearly referenced in the scriptures. The above list provides clear examples from of Old Testament persons, objects or events that in the New Testament are explicitly referenced as relating to the Lord Jesus Christ as the antitype.
The safest approach to typology is to restrict types to only those that are clearly called out in scripture. Anything beyond that quickly moves into the realm of conjecture and opinion. It may be that there are types beyond those God has revealed in the scriptures, but the student of the scriptures should be hesitant to dogmatically insist that something must be a type that is not clearly delineated as such in scripture.
[1] F. W. Danker, 2000, A Greek-English Lexicon of the New Testament and other Early Christian Literature. The University of Chicago Press, Chicago.