The account in Matthew 9:9-14 appears both in Matthew and Luke (Q). The call of Matthew (v.9) is worded in a way similar to the preceding call of the fishermen (4:18-23). But while this latter shows that the response to the Word of Jesus is a response made in life (=Discipleship), the call of Matthew taken with vv. 10-13 as its immediate context, illustrates an aspect of the call of Jesus: it is addressed, not to the righteous, but to sinners.
The righteous are represented here by Pharisees, who contrast themselves with "tax collectors" and "sinners." The Pharisees, together with the Sadducees, were the ones who considered themselves above the ritual cleansing offered by the Baptist (Mt. 3:7). They were of course, the Separated Ones, separated from the rest of the common folk because of their adherence to the Law. They were always, by practice, ritually clean and expected religious leaders to do the same.
The clean cannot mix with the unclean. Jesus, however, was not thinking in terms of clean-unclean; he was thinking in terms of sickness-cure (or of losing-finding, cf. Mt. 12:11). The Hosean (Hos 6:6) phrase he quotes is a call for a religion that goes beyond ritualism and a concept of God that is bound up with the laws of nature (see context in Hos. 6:1-3 and following), and whatever ritual law there may be.
The disciple is a sinner who responding to Christ's call, makes Him the central value of his/her life.
Note 1: In his account of the call of Matthew (=Levi), Luke takes away the reference to Hosea and adds "..to repentance."
Note 2: Tax collectors were considered unredeemable because they collaborated with the Roman Empire in exacting tax from Israel. Their work made them "enemies of the people."
