There are a number of criteria for determining whether an element in a catechetical account contains anything historical, and not a simple affirmation of faith by the evangelists. There are five main criteria which are used to judge the historical value of a narrative, and five secondary criteria which are only valid after having used the main criteria, and are not valid in themselves

1. Primary Criteria

   1. The Criterion of Embarrassment

      The first criterion concerns the annoying elements of the narrative, i.e. elements that Christians would have had an interest in removing and do not fit in with their catechesis. A first example: the baptism of Jesus by John the Baptist, which Christians considered to be inferior. If Mark mentions it, Luke and Matthew on the other hand avoid any detail and John eliminates it. A second example: the ignorance by Jesus of the eschatological hour when the universe will colapse. If Mark mentions it, some versions of Matthew omit it, and Luke ignores it. Rather, the Gospel of John says the opposite, saying that Jesus knows the present and the future. Thus, an annoying element is most likely not to have been created by Christians and so is deemed to be historic. However, this criterion must be handled with care, since the troublesome elements are few, and determining what was also troublesome in the time of Jesus, not only for our time, requires analysis.

   2. The Criterion of Discontinuity

      The second criterion is that of a discontinuity both in relation to Jewish thought and to the thought of the early Christians, and therefore would present us with something that can only come from Jesus himself. Some examples: Jesus' rejection of voluntary fasting practiced by Jews and Christians, his position on divorce. Even if it is not easy to know the milieu of the first century to make this type of analysis, there has been so much work on this period that one can be today confident to affirm that, if a point of the Gospels does not fit neither with the Jewish milieu nor with the Christian milieu, it has good chances to go back to Jesus and to represent one of its characteristics.

   3. The Criterion of Multiple Attestation

      The third criterion is that of multiple attestation: when an element is found in more than one independent literary source (ie we consider Mark as an independent source, Document Q used by Luke and Matthew, John, and Paul) or more than one literary genre, it is likely to be historic. An example: all the sources show Jesus proclaiming the Kingdom of God, including Paul who does not like this expression very much. Other examples: the Last Supper with the words on bread and wine, or the announcement of the destruction of the temple. However, this criterion is not foolproof and must be used with the other criteria. And it can happen that an element that is found in a single source (like the Aramaic word Abba to designate God) is likely to be historical.

   4. The Criterion of Coherence

      The fourth criterion of coherence (or conformity) can be used when we have succeeded in isolating with the previous criteria elements which seem historical: all these elements must form a coherent whole, while recognizing that our Western logic has its limits.

   5. The Critrion of Rejection and Execution

      The fifth criterion is different from the others and uses the fact that Jesus was rejected by the Jewish and Roman authorities and was put to death, and therefore obliges us to examine the causes of this rejection and execution. Jesus cannot have been just a dreamy poet. This fact therefore imposes a setting for determining the historical Jesus.

2. Secondary (or Dubious Criteria)

   6. The Criterion of Traces of Aramaic

      Even if Aramaic was the language spoken by Jesus, there is no point in trying to piece together an Aramaic text underlying the Gospel accounts. First of all, the current Greek versions vary a lot and make this reconstruction impossible. Then, the first Christians spoke Aramaic, and therefore this fact prevents us from determining whether this or that passage is from Jesus or from the first Christians.

   7. The Criterion of Palestinian Environment

      The problem with this criterion is that Palestinian customs as well as the legal, commercial and agricultural practices of the time of Jesus continued to exist long after his death and prevent us from distinguishing what is proper to Jesus and what is proper to the early Christians. Conversely, a non-Palestinian environment clearly shows that an element does not belong to Jesus.

   8. The Criterion of Vividness of Narration.

      The problem with this criterion is that it is impossible to disentangle what belongs to the historical fact and what belongs to the talent of the narrator. In addition, a vivid detail can go back to an oral tradition as well. Conversely, the absence of vivid and concrete features does not mean that a story has no historical value.

   9. The Criterion of the Tendencies of the Development Synoptic Tradition

      This criterion was promoted by the German theologian Bultmann. According to this criterion, evangelical narratives would tend over time to amplify with concrete details, names of characters, speeches in direct style. If such an evolution existed, then it would be possible to go back in time to the original narrative. The problem with this criterion is that it is based on a hypothesis impossible to prove and that, even if the hypothesis were true, it would simply put us in front of an original story created by a writer.

   10. The Criterion of Historical Presumption

       According to this criterion, everything is historic unless proven otherwise. But the question arises: who bears the burden of proof, the proponents of historicity or the proponents of non-historicity? Obviously, the burden of proof is on anyone who wants to prove anything. In short, ready-made evidence does not exist.