Manners of Dawah

Don’t ever make fun of a person who has fallen into sin. Advise them nicely. Don’t try to put them down. 
If you haven’t fallen in that sin, it is only  because Allah alone protected you. 
Some people attribute success to themselves...some boast about ‘themselves.’
If you make fun of some person who commits certain sins, you don’t know, maybe you will fall into those sins. 
Maybe you may be punished for your hurtful words if you did hurt certain people. 

May Allah protect us. 

Don’t ever taunt someone who has already repented. Learn from the story of Yusuf 
عليه السَّلام
and his brothers. 
You will never hear of any Nabi taunting a person for their past when in fact that person has done Tawbah and regrets a lot. 
Have you forgotten the story of so many Sahabah 
رضي اللهُ عنهم
?
We should learn lessons from the stories mentioned in the Qur’aan and the Sunnah and apply the lessons. 
May Allah guide us.