The sin of rebellion, rejecting God. vv22-25
Here Jesus is not saying that people didn’t have sin before He came, nor that He caused sin. What HE is saying is that the rejection of Jesus is their sin. In ways, it is the ultimate sin.
Matthew 12 and Mark 3 record Jesus talking about an unforgivable sin. Rejecting Jesus is this sin. Any sin is forgivable and has been overcome by Christ’s death on the cross. However, rejecting Christ closes the door on this forgiveness. That is why it is unforgivable. Jesus here says that those who have seen (or heard) of what Jesus did but decide to reject it. They will be held accountable for their sin.
Our response to the hatred and persecution from the world is NOT to remain silent. Nor is it a good idea to avoid speaking of Jesus to spare people guilt. People need the forgiveness and hope that we have in Jesus. Many, perhaps most, will not accept His love, but our job is to stand firm in hope.