Jews, including Jesus, went through regular cycles of being clean and unclean, but this was not considered a sin, especially because you could easily become unclean through no fault of your own. Jesus became unclean when he was touched by the woman with severe bleeding or when he healed people with leprosy. If someone was in a room with a group of other people and one of them has a heart attack a died, then they and everyone else in the room would become unclean. They could then go home and eat a kosher meal, which would then become unclean because they were touching it, but they wouldn't be sinning. However, if they were to enter the presence of the Lord or perform other Temple services while unclean, then they would be sinning. If you've ever gone to a funeral with an open casket or been touched by someone who has, then you are currently unclean.
