Jesus was talking about following religious practices with some people. He told them that at different times, we need to adjust our practices. Like when God reveals something new to us.
He used two metaphors to illustrate this. The first was patching a hole in an old piece of clothing with new material. If one sews a patch on an old item of clothing, when it is washed, the patch will shrink, pull on the old fabric, weaken it, and, eventually, create a bigger hole.
The second was putting new wine into old leather skins. Fermentation causes gas to form. The gas will stretch the leather skin. New skins will stretch; old skins will not. Stretching the old skins will cause them to burst. Ruining the skins and the wine.
Pretty often, I read, hear or see some Christian announce that God is going to do something new. He will reveal himself differently. He will reveal his purposes in a new way. If these proclamations are true, then, according to Jesus, should we not be making adjustments in our practices? Should we not be acting differently?
(I have heard that old leather can be treated in a way that it will regain its suppleness and elasticity. But doesn't that mean someone has to do something different?)
The basic form of doing church has been set for hundreds of years. There have been some changes. The music is different. Many churches no longer use special robes. People still meet in special buildings. They are still led by professionals. The focus still is on the weekly meeting. Most people are still spectators. There is a fixed time of singing and prayer. Then, someone gives a speech.
I do not mean to suggest that any of these things are bad or evil somehow. But, if God is doing something new, then we need to do something new.