Jewish law forbade touching lepers (Lev 5:3) and quarantined lepers from regular society (Lev 13:45-46); people avoided most contact with them (2 Kings 7:3; Jos. Ant. 9.74). Some ruled that the defilement of leprosy was one of the greatest defilements, for a leper could communicate it even by entering a house (m. Kelim 1:4). It is thus no small matter for Jesus to compassionately touch the man. Yet by touching Jesus does not actually undermine the law of Moses, but fulfills its purpose by providing cleansing (Mt 5:17-48; compare Lev 13:3, 8, 10, 13, 17).
Some Christians today would fear to touch a Christian brother or sister who, through blood transfusion, past lifestyle or a spouse's infidelity, was HIV-positive, even though HIV is less contagious than many people thought leprosy was. As often happens today, some people in antiquity constructed theological rationalizations for others' misfortune perhaps to escape from the fear that they too were vulnerable; hence some later teachers decided that leprosy was divine punishment (m. Seqalim 5:3; Lev. Rab. 17:3).
Jesus Wants to Make the Man Whole (8:3)
Verse 3 implies what is elsewhere explicit: Matthew views compassion as a primary motivation in Jesus' acts of healing (9:36). Even if in some cases God has some higher purpose in mind than an immediate answer to our request (as in 26:39, 42), he is never sadistic. Jesus demonstrated his feeling toward our infirmities by bearing them with us and for us (8:17) and by healing all who sought his help (8:16). Matthew hardly expects us to suppose that Jesus has lost any of his power (28:18) or compassion since the resurrection. Unfortunately, many of us Western Christians today feel more at home with the Enlightenment rationalism in which we were trained than we do with the desperate faith of Christians who dare to believe God for miracles. Those in desperate need cannot afford to rationalize away God's power and compassion.