In our modern time, we rarely hear the word "wineskins". However, in the setting of this parable, speaking of old and new wineskins gave the hearer a perfect word picture. What Jesus was really referring to was the new wineskins/the Gospel not just becoming a added part of the old wineskins/the traditions and religious system of Judaism. The overall, bottom line truth is in the uniqueness of the gospel. Christianity is a one-of-a-kind, exclusive way of life. It is incompatible; unmixable.
