Matthew 3:2 and saying, “Repent, for the kingdom of heaven is at hand!”
3 For this is he who was spoken of by the prophet Isaiah, saying: “The voice of one crying in the wilderness: ‘Prepare the way of the LORD; Make His paths straight.
First off, Johns ministry was prophesied many hundred years beforehand. He was to prepare the way for the LORD. To set straight, the path, which means the paths were crooked. Those who presented the paths to heaven were crooked.
Secondly, he came preaching for men to repent, turn from the path they are currently on, and recieve the Kingdom of God, which is now here. How exciting the message John got to give. How exciting it was for me when I first heard this message. My hearts still overjoyed. This message is still alive today. This message goes deeper than religious duties and straight to our hearts. His kingdom is actually here. He can be the King of my heart. He will one day, establish His kingdom here on Earth, and physically reign as King.