The Jews would not permit either leavened fruit of the vine or bread at the Passover. Even when wine was used under the Law for animal sacrifices, it was poured out at the base of the alter. A priest who began to ferment and bubble like new wine would violate the Law. The Jews even had a law for a priest who ate grape seed. New wine will ferment in contact with an old, contaminated skin.
New cloth becomes old cloth by shrinking .
As it does it taketh from the old cloth and the rupture occurs. Change, either expansion or contraction, in the product takes place before the damage is done. The command or type is exactly like the fulfillment in the teachings of Christ. Therefore, the new wineskin means that the church must not break down the walls to allow the leaven of fellowship with destructive leaven during worship to enter in. When the people in Isaiah 5 turned their food which was the product of the vine into the product of the vat, God removed and broke down the walls of His Divinely-given Vineyard.