James Edwards: The scandal of this story [Mark 2:13-17] is that Jesus does not make moral repentance a precondition of his love and acceptance. Rather, Jesus loves and accepts tax collectors and sinners as they are. If they forsake their evil and amend their lives, they do so, as did Zacchaeus (Luke 19:1–10), not in order to gain Jesus’ favor but because Jesus has loved them as sinners. Jesus’ association with such people is not coincidental. He does not happen to be with them or wait for invitations. He initiates the fellowship, “‘I must stay at your house today’” (Luke 19:5). We are not told how many sinners and tax collectors repented and reformed. We are only told that Jesus sowed love as profligately and uncalculatedly as the sower who threw seed in unpromising places (Mark 4:3–9). It is this that scandalized the religious leaders of his day, as it scandalizes those who define the gospel in terms of pure moral reformation and character formation of our day. Jesus communicates in word and deed that accepting and following him are more important than following Torah. When the unreformed and unregenerate do that, they will enter the kingdom of God before the scribes and Pharisees. In table fellowship with “sinners and tax collectors,” Jesus scandalously asserts his exousia, his own person over Torah, and the profligate love of God over merit. That is the scandal of grace.
— Edwards, J. R. (2002). The Gospel according to Mark. The Pillar New Testament commentary (85–86). Grand Rapids, Mich; Leicester, England: Eerdmans; Apollos.