Jesus' woes are the angry laments of wounded love, incited by compassion for those whom religious leaders have led astray (see 23:37). Second-century rabbis, probably passing on many ideas from the Pharisees of Jesus' day, harshly condemned hypocrisy (for example, t. Yoma 5:12). Christians today often think of "Pharisees" as hypocrites and hence do not feel threatened when hearing them denounced. But the Pharisees' contemporaries thought of them as very devoted practitioners of the Bible, and of the scribes as experts in biblical laws. In today's terms, Jesus was thundering against many popular preachers and people who seemed to be living holy lives--because they were practicing human religion rather than serving God with purified hearts.
I suspect that much of what passes for Christianity today is little more than human religion with the name of Jesus tacked onto it, because like most of the religion of Jesus' contemporaries, it has failed to transform its followers into Christ's servants passionately devoted to his mission in the world. When rightly understood, Jesus' woes may strike too close to home for comfort. When religion becomes a veneer of holiness to conceal unholy character, it makes its bearers less receptive to God's transforming grace.
They are eager to make converts, but their converts simply mimic and accentuate their flaws. (One thinks by contrast of the stone-drunk man who told D. L. Moody, "I'm one of your converts," to which Moody reportedly replied, "I can certainly see you're not one of the Lord's.") Although Judaism had no central sending agency, hence no "missionaries" in the formal sense, plenty of evidence testifies that many Jewish people were winning Gentiles to Judaism (for example, Jos. Ant. 20.17, 34-36; Apion 2.210; Tac. History 5.5). Jewish people actively courted many conversions in the Gentile world until Christian emperors began enforcing earlier Roman laws to shut down Jewish proselytism (see Jeremias 1958:11-12). Presumably by exposing converts to the truth of God's standards while allowing hypocrisy through their own bad example (23:3, 13), these Pharisees were leading their converts to be doubly damned.
As in 23:19, Jewish people viewed the altar as consecrating whatever was offered on it (Bonsirven 1964:124). Pharisees may have prohibited swearing by the gold of the temple because they believed that it, unlike the temple or the altar, was subject to lien (Gundry 1982:463); in any case, Jesus rejects their reasoning. Jesus rails in part against traditions that have created inconsistent standards of holiness. (We might compare churches today that rightly condemn smoking or overeating as polluting the body yet remain silent on watching television programs that pollute the mind. Some traditional churches regard particular styles of clothing or music as "worldly" yet harbor jealousy, materialism and other attitudes the Bible explicitly condemns as worldly. Some churches fight for the authority of Scripture yet care so little for it in practice that they ignore the context of verses or explain away passages that seem too difficult, like God's demand that Christians care for the poor or witness to their neighbor.) But Jesus' attack is ultimately directed against the profanation of God's name. Because any surrogate oath nevertheless represents God's name and implicitly calls him to witness, any breach of truthfulness demands judgment no less severe.
Pharisees were particularly known for their scrupulousness in tithing (as in ARN 41A; Borg 1987:89). Building their fence around the law, these religious people were careful about tithing even substances whose status as foodstuffs was disputed, so that it was not clear whether the Old Testament agrarian tithe applied to them (compare Jeremias 1969:254). Jesus accepts that the leaders should have kept these biblical laws but insists that they have missed the forest for the trees (compare 7:3-5); their neglect of the law's basic requirements (Deut 10:12-13; Mic 6:8) is inexcusable.
Like Jesus, most Jewish teachers recognized some commandments as more important, literally "weightier," than others (compare Johnston 1982:207). Although he, like his contemporaries, regarded no commandment as light (see comment on 5:19; compare Jas 2:10-11; m. 'Abot 4:2), Jesus himself taught much about "weightier" matters, even in this context (Mt 23:5, 17, 19). Today as well, many of us separate from or condemn other Christians on the basis of our interpretations of isolated passages while neglecting broader principles (like charity or the equal standing of all believers in Christ).
Jesus illustrates the inconsistency in verse 24 with a witty illustration about Pharisees who were more scrupulous than Pharisaic legal rulings required. If a fly fell into one's drink, Pharisees taught that it must be strained out before it died, lest it contaminate the drink (compare Lev 11:34); but they decided that any organism smaller than a lentil (such as a gnat) was exempt (E. Sanders 1990:32). Since most of us today would not want a gnat dying in our drink either, we may have sympathy with a Pharisee who for a different reason--passion for purity--went beyond the letter of the law to remove it (see E. Sanders 1990:38). Nevertheless, these Pharisees were so inconsistent, Jesus said, that they concerned themselves with purity issues as trifling as a gnat but did not mind swallowing a camel whole. In ancient writings gnats are cited as the prototypically smallest of creatures (Ach. Tat. 2.21.4-5; 2.22); camels, which were explicitly unclean under biblical law (Lev 11:4), were the largest animal in Palestine (see comment on 19:24).
Although Jesus speaks metaphorically about the inside of a cup (that is, the human heart) in Matthew 23:25-26, he may allude to a matter of some debate among his contemporaries. The Shammaite school of Pharisees were less concerned whether one cleansed the inner or outer part first. In contrast, the Hillelite Pharisees thought that the outside of a cup was typically unclean anyway and thus, like Jesus, insisted on cleansing the inner part first (Neusner 1976:492-94; m. Berakot 8:2). On the surface Jesus' statement challenges Shammaite practice (though for the effect of the metaphor); but he actually addresses the purity of our hearts, a point he reinforces in his next illustration.
Although dead creatures in a beverage produced impurity (23:24), corpse uncleanness (v. 27) was more severe, extending seven days (Num 19:11-14; Jos. Ant. 18.38; m. Kelim 1:4). If so much as one's shadow touched a corpse or a tomb, one contracted impurity (E. Sanders 1990:34, 232). Although Jesus may have originally alluded to the springtime practice of using whitewash to warn passersby and Passover pilgrims to avoid unclean tombs lest they become impure and hence barred from the feast (m. Mo`ed Qatan 1:2; Ma`a'ser Seni 5:1; Seqalim 1:1), as in Luke 11:44, Matthew focuses on an incidental effect of the marking. For him whitewash is a beautifying agent to cover a tomb's corruption (borrowing the image from Ezek 13:10-12). The leaders' outward appearance (compare Mt 23:5, 28) merely provided a veneer for the impurity, hence lawlessness (literally; NIV wickedness), of their hearts. To those who prided themselves on obedience to Torah, the charge of lawlessness would be deeply offensive and shaming.
Employing irony in a manner typical of the prophets (who sometimes told the people to go on sinning but to expect God's judgment for it--Is 6:9; 29:9; Jer 23:28; 44:25-26; Ezek 3:27; Amos 4:4-5), Jesus tells the leaders to fill to the brim the role of prophet murderers they have inherited, so that the judgment accumulating for generations will finally be poured out (Mt 23:36).