Matteo 9:17

Neither do men put new wine into old bottles; else the bottles break, and the wine runneth out, and the bottles perish. But they put new wine into new bottles, and both are preserved.

Just as Christ had emphasized the fitness of things in His apology for the disciples, He here insists upon proper congruity in religion, especially in external forms. To put a patch of unsecured, new and strong, cloth upon an old garment will usually result in disaster, since the patch, being stronger, will tear out at the edges, thus making the rent worse. The piety of the Pharisees, the religion of works which they flaunted before the eyes of the people, on the one hand, and the doctrine of Jesus, the preaching of the free grace of God through His blood, on the other, will never agree.

If one insists on wearing his old garment of self-righteousness and works, and then believes it possible to cover an occasional revealing sin with the Gospel, he will find but poor comfort. His heart is still bound up in the old garment, and his miserable subterfuge will only make the incongruity appear the more glaring. It is just as foolish to keep new wine, grape-juice in the early stage of fermentation, in old skins that have lost their elasticity.

The result is disastrous: The skins burst, the wine is spilled. But new skins and new wine are perfectly suited to each other. The sweet Gospel of the forgiveness of sins by the mercy of God does not fit into carnal, Pharisaic hearts. If the Gospel is preached to those that believe in works only, its richness is squandered. Such hearts cannot understand or keep it; they only take offense at the preaching of the Gospel, and are lost in spite of the Gospel. Only meek and lowly, believing hearts will accept the Gospel just as it reads, and will be kept by the power of God unto salvation.