I took the small scroll and swallowed it, and although it tasted sweet in my mouth, it turned sour in my stomach. As the narrations (revelations) continue, John relays a vision in which he once again finds himself the recipient of the message from the Lord. However, this time, he becomes both a recipient and a messenger. He is commanded to ingest a scroll containing the Word of God after which he was to go and prophecy. As he narrates, while the scroll tasted as sweet as honey in his mouth, it turned sour in his stomach. And it is at this moment that a voice commands him to go and prophecy once again. While we are not told what the content of his prophecy was to be (there is an assumption that we already know), there is a connection between the message and the scroll. 
The scroll contained the word of God. It is this very word of God that is the content of any prophecy. The word of God tastes sweet when it hits our ears for it is a word of emancipation, hope, and second chances. But the word of God also challenges us to embrace our fears and weaknesses, especially those that keep us away from our brothers and sisters. As if that is not enough, this is also the content of the message a prophet has to relay. It is at such moments that the word of God turns sour in the stomachs of prophets, as Jesus Christ found out in our Gospel reading today. 
As a prophet, Jesus’ words and actions offer a challenge to his listeners, something about which they are not overly enthusiastic. The prophet has constantly reminded them of their call to charity and holiness in their lives. He has constantly reminded them that their election as a special people carried with it a responsibility. And it is this that lands Jesus in trouble. While his listeners liked the idea of being God’s elect, they were not overly passionate about the responsibility that came with it. They forgot that the word of God that we receive always calls us to action, an action that will often take us outside our comfort zones.