When the people of Jesus's time spoke of "sinners," they were talking about people who did not obey the law of Moses and instead committed sins like stealing or sexual sins. When Jesus said that he came to call "sinners," he meant that only people who believe that they are sinners can be his followers. This is true even if they are not what most people think of as "sinners." (See: [[rc://en/tw/dict/bible/kt/sin]])
People would fast, or not eat food for a long time, when they were sad or were showing God that they were sorry for their sins. When they were happy, like during weddings, they would have feasts, or meals where they would eat much food. (See: [[rc://en/tw/dict/bible/other/fast]])
The Jewish leaders used rhetorical questions to show that they were angry because of what Jesus said and did and that they did not believe that he was God's Son ([Mark 2:7](../../mrk/02/07.md)). Jesus used them to show the Jewish leaders that they were arrogant ([Mark 2:25-26](./25.md)). (See: [[rc://en/ta/man/translate/figs-rquestion]])