Jesus was without sin but He is and ever will be, the only human who has ever been in that state.

Jesus was about forgiving sinners, not stoning them.

Jesus forgave the woman but she would have had to deal with her husband and family so like us all, she would have suffered for her sin. 

Under the law, Nicodemus could not justify the arresting of Jesus for the words He spoke.

Nicodemus and the officers also were impressed with what Jesus spoke and not convinced by the words of the rulers or Pharisees.