"Bottles" in this verse is better rendered literally wine-skins ( ἀσκούς). And no man putteth new wine ( οἶνον νέον) into old wine-skins; else the new wine will burst the skins, and the wine perisheth, and the skins; but they put new wine into fresh wine-skins ( ἀσκοὺς καινοὺς).
The sense is this: New wine, in the process of fermentation, will burst old bottles made of wine-skins not strong enough to resist the strength of the fermenting fluid; so that there is a twofold loss—both that of the bottles and that of the wine.
And therefore new wine must be poured into bottles made of fresh wine-skins, which, by reason of their strength and toughness, shall be able to resist the fermenting energy of the new wine. And by these very apt illustrations our Lord teaches us that it is a vain thing to attempt to mingle together the spiritual freedom of the gospel with the old ceremonies of the Law.
To attempt to engraft the living spiritual energy of the gospel upon the old legal ceremonial now about to pass away, would be as fatal a thing as to piece an old garment with new material, or to put new wine into old wineskins.
There is here, therefore, a valuable lesson for the Christian Church, namely, to treat new converts with gentleness and consideration.