The stories in Matthew 15-16 begin with a challenge to Jesus (15:1-20) and end with another demand for a sign (16:1-12), both stories include a stinging rebuke of the Pharisees for their reliance on their own traditions. The two stories between in which Jesus encounters remarkable faith among the Gentiles. Jesus is not “turning to the Gentiles.” On the contrary, the two stories contrast the remarkable faith and openness to the Jewish Messiah from the Gentiles with the lack of faith from the Pharisees.
In Matthew 9:14-17 the Pharisees questioned Jesus’s disciples about his non-practice of fasting. In Matthew 12:1-14 they question Jesus’s activity on the Sabbath (his disciples glean, and he heals on the Sabbath). This results in the Pharisee’s pronouncement Jesus casts out demons by the power of Beelzebub (12:22-24) and the demand or a sign (12:38). This sequence represents a break with the Pharisees and Jesus turns to teaching the crowds in parables for the first time in Matthew because the present generation has become like the people in Isaiah 6:8-9, always seeing, never understanding (13:11-17).
There are several important changes from Mark 7, including the explanations of hand washing and corban, both added in Mark to explain a Jewish tradition to a non-Jewish audience. Another significant deletion is Mark’s comment that Jesus declared all foods clean. Remarkably, Craig Blomberg titles Matthew 15:1-20 as “Kosher Laws Rescinded” in his NAC Matthew commentary. Kosher food (or not) is not the subject in Matthew, but rather the traditions of the elders.
The Pharisees and scribes approach Jesus and ask about his disciples not washing their hands (15:1-2). These Pharisees and scribes come from Jerusalem to Galilee, indicating Jesus’s reputation has reached religious authorities in Jerusalem. The problem is Jesus’s disciples do not follow the “traditions of the elders.” This phrase can be used for the legal decisions made by respected teachers of the Law in the Second Temple period (Antiq. 13.10.6), but here refers specifically to the oral tradition curated by the Pharisees.
The problem with eating with unwashed hands is that it will render the food unclean and eating unclean food makes a person ritually impure. If you are in a state of cleanliness, but you have touched something or someone who is unclean, then your hands are unclean and that will defile your food. The solution, for the Pharisees, was to always ritually wash one’s hands before eating.
The Mishnaic tractate m.Yadim (“Hands”) describes various ritual washings, although this dates to at least AD 250. This tractate covers washing of hands as a process of purification and is different than immersion in an immersion-pool (miqveh) for purification from uncleanness. For example, in Jubilees:
Jubilees 21:16–17 “Wash thyself with water before thou approachest to offer on the altar, and wash thy hands and thy feet before thou drawest near to the altar; and when thou art done sacrificing, wash again thy hands and thy feet.”
As much as possible, they were practicing the kind of separation from uncleanliness required of a priest working in the Tabernacle (Exod 30:19, 40:13) in everyday life. “the analogy between the domestic table and the Temple altar which is probably the source for the requirement to wash hands before eating” (Neusner, A History of the Mishnaic Law of Purities, 19:104).
Although Aristeas 305 says “all the Jews washed their hands and prayed to God” (cf. Judith 12:7, Sib.Or. 3.591-583), only the Pharisees sought to create “in everyday life the conditions of purity required in the Temple” (Jacob Neusner, “‘First Cleanse the Inside,’” 494, n. 2). The average Jewish person would avoid contact with uncleanliness but would not overly concern themselves with accidental contact with unclean things.
Some Jews think food could defile a person, see, for example 4 Maccabees 7:6.
4 Maccabees 7:6 O priest, worthy of the priesthood, you neither defiled your sacred teeth nor profaned your stomach, which had room only for reverence and purity, by eating defiling foods.
Why would the Pharisees think Jesus and his disciples ought to conform to their traditions? By analogy, an Amish person probably does not get too upset when an Episcopalian does not follow their traditional practices (they probably assume they are going to hell and not worry too much about it).
But since Jesus is closest to Pharisees in terms of theology, they may have thought of Jesus as one of their own, or close enough to ask the question. If the Pharisees had the sense Jesus was claiming to be the Messiah, then certainly the Messiah would follow their interpretations of the Law!
Bibliography: Jacob Neusner, A History of the Mishnaic Law of Purities: Tebul Yom and Yadayim, ed. Jacob Neusner, vol. 19, Studies in Judaism in Late Antiquity (Eugene, OR: Wipf & Stock Publishers, 2007). Jacob Neusner, “‘First Cleanse the Inside,’” NTS 22 (1975–76) 486–95; 494, n. 2. See also G. J. Wenham, “Christ’s Healing Ministry and His Attitude to the Law,” Christ the Lord (ed. H. H. Rowdon; Leicester: InterVarsity, 1982).