37And no one pours new wine into old wineskins. If he does, the new wine will burst the skins, the wine will run out and the wineskins will be ruined. 38No, new wine must be poured into new wineskins.
Take note that this is a continuation of the parable of the old garment and new garment, hence Jesus is trying to say the same thing but this time using the analogy of old wine and new wine, and old wineskins and new wineskins.
What is the meaning of the wine and wineskins? Jesus referred to wine as blood in Luke 22:17-20 :
17After taking the cup, he gave thanks and said, "Take this and divide it among you. 18For I tell you I will not drink again of the fruit of the vine until the kingdom of God comes."
19And he took bread, gave thanks and broke it, and gave it to them, saying, "This is my body given for you; do this in remembrance of me."20In the same way, after the supper he took the cup, saying, "This cup is the new covenant in my blood, which is poured out for you.
This new wine is meant for everyone to receive righteousness through faith in Jesus' blood sacrifice; it is a separate path to God, a separate path from the law - "But now a righteousness from God, apart from law, has been made known, to which the Law and the Prophets testify. This righteousness from God comes through faith in Jesus Christ to all who believe." (Romans 3:21-22) - this is a totally new covenant, therefore this new wine cannot be poured into old wineskins i.e. the law.
Those who believe in the gospel of grace (i.e. pour the new wine in new wineskin) truly uphold the law because they let the law be the law. That is why Romans 3:31 says "Do we, then, nullify the law by this faith? Not at all! Rather, we uphold the law."
If we insist on pouring the new wine into old wineskins i.e. mixing grace with the law, then the old wineskin will burst and the new wine spilled onto the ground. Both are ruined, the law is no more the law and grace is no more grace, as Romans 11:6 says "And if by grace, then it is no longer by works; if it were, grace would no longer be grace."
Christians have no problem believing in the new wine, they just cannot believe in the new wineskin, which is why Jesus didn't bother to warn us not to pour old wine into new wineskins. However, Jesus commented in Luke 5:39 "And no one after drinking old wine wants the new, for he says, 'The old is better.' " because the Jews in Jesus' time on earth still believe in the old wine i.e. the blood of bulls and goats. They cannot see or taste the new wine that Jesus will bring until after the cross. Even today, after the cross, many Israelis still say the old wine is better.
But Jesus, right at the start of his earthly ministry, has already declared to the world that the new wine tastes better, nay, the best! John 2:1-11 records the very first miracle by Jesus at a wedding feast where he turned six stone water jars filled with water into wine!
How did this brand new wine taste? "and the master of the banquet tasted the water that had been turned into wine. He did not realize where it had come from, though the servants who had drawn the water knew. Then he called the bridegroom aside 10and said, "Everyone brings out the choice wine first and then the cheaper wine after the guests have had too much to drink; but you have saved the best till now." " (John 2:9-10)
Friends, don't waste this best wine by pouring it into old wineskins!