By quoting Isaiah 6:9-10 in his explanation why he teaches in parables (Mark 4:10-12), Jesus indicates that nothing has really changed about Israel since Isaiah’s day. They see but do not perceive, they hear but do not understand; that is, they are still afflicted with unbelief. Jesus’ ministry through parables has the same role as Isaiah’s ministry, namely hardening Israel further, so that God’s purposes of judgment might be fulfilled. But, at the same time, there will be a holy seed, a remnant, raised up from Israel, who hear, and see, and understand. Hearing the word with acceptance, this remnant will be the seed that enters the coming harvest of the kingdom of God.
But this remnant of believers will be raised up against the backdrop of the general unbelief of Israel. The people of Nazareth provide an example of the unbelief of Israel. Well aware of Jesus’ might works, they nevertheless fail to believe, because he is just too familiar to them (Mark 6:1-6).
-Peter Bolt, The Cross From a Distance: Atonement in Mark’s Gospel (p. 35-36)