First, Jesus did sit with open sinners and He did treat them kindly. But He also told them to stop openly sinning or they were going to die the second death.
What is the second death?
This is a popular rebuke from people who don't really understand the Bible. I'm talking about the person who says, don't rebuke sin, don't expose it, because Jesus ate with sinners. Yes, and He told them the truth. And you better believe that a lot of those sinners who wanted to see what this Jesus had to say, turned from Him in anger and mocking what he said. Most of them did. Most people are on the broad path. So that's how we know that only a few accepted what Jesus said.
But then you have to deal with people who claim that Jesus Christ was just nice to people who intentionally, openly reject Him and Our Father which is in heaven. No: Jesus basically told them as He's telling you and me: "I love you, I died for you, I'll save you, but I am the only way to the true and living God."