Mark 2:22 (NIV): And no one pours new wine into old wineskins. Otherwise, the wine will burst the skins, and both the wine and the wineskins will be ruined. No, they pour new wine into new wineskins.”

What Jesus is doing can’t be fitted in to the existing ways of thinking and living. If people try to do that they’ll have the worst of both worlds. At the time, this meant that Jesus’ powerful kingdom-ministry couldn’t be fitted into the ways of thinking that his fellow first-century Galileans already had. They needed to think differently, to think bigger, to get new wineskins for the new wine he had to offer. Most people are threatened by that kind of challenge. (NT Wright, Mark for Everyone)