The Gate Is Narrow

"The law & the prophets were proclaimed until John; since that time the gospel of the kingdom of God has been preached, and everyone is forcing his way into it." Luke 16:16

The law and the prophets were until John. With these words, the Lord described the legal dispensation which began with Moses and ended with John the Baptist. But now a new dispensation was being inaugurated. From the time of John, the gospel of the kingdom of God was being preached. The Baptist went forth announcing the arrival of Israel's rightful King. He told the people that if they would repent, the Lord Jesus would reign over them. As a result of his preaching and the later preaching of the Lord Himself and of the disciples, there was an eager response on the part of many.
Everyone is pressing into it--those who did respond to the message literally stormed into the kingdom. The tax collectors and sinners, for instance, had to jump over the roadblocks set up by the Pharisees. Others had to deal violently with the love of money in their own hearts. Prejudice had to be overcome.
But the new dispensation did not mean that basic moral truths were being discarded. It would be easier for heaven and earth to pass away than for one tittle of the law to fail.

From William MacDonald's Believer's Bible Commentary on Luke 16:16