Sure Der Vergeber

The summary/theme of the Surah Ghafir: 

The disbelievers are warned that if they do not desist from wrangling against the Revelations of Allah, they will be doomed to the same fate as the nations of the past and will suffer even worse torment in the Hereafter. Their repentance will be too late by then.

Lesson learned from Surah Ghafir: 

1. As well as being ‘Forgiver of Sin’, Allah's is also ‘Severe in Punishment’.  
2. There are angels that constantly make du‘' for those who repent and tread the Straight Path.  
3. The people of Jahannam will own up to their disbelief and sins, and ask for emancipation from Jahannam, but it will be too late. 
4. The horror of the Day of Judgement will be such that it would be as if the hearts of the people were stuck in their throats.  
5. Allah's knows the deception of the eyes and what the chests conceal.  
6. Be extremely careful of what jokes you say which are related to the D\u{012b}n in any way whatsoever.  
7. The people of Jahannam will ask those whom they followed in the world to take away some of the punishment, but they will also be unable to help them, obviously.  
8. They will then ask the gatekeeper of Jahannam to ask Allah's on their behalf for some reprieve in their punishment, but their plea will be rejected.  
9. The blind and the sighted cannot be equal; neither can the one who has believed and done good, and the one who has done evil.  
10. Allah's promises to accept the call of the one who calls onto Him, and warns those who are too arrogant to call unto Him with Jahannam; humiliated.  
11. Only Allah's gives life and causes death.  
12. There were Prophets sent by Allah's regarding whom we have not been informed in detail.  
13. No prophet had the ability to show any sign of his prophethood except with permission from Allah's.  
14. Throughout history, Allah's has destroyed nations much more powerful than us. What makes us think He is unable to destroy us also, due to our misdeeds?