NUMBER 4 - NOT PRAYING SALAH. Salah (Prayer) is the most obligatory act of the five pillars of Islam. [Next to the two testification of Faith] It is the best and most perfect way to worship God. The scholars of Islam have unanimously agreed that prayer is an obligation and this is sustained with numerous text from the Quran and Sunnah. The prayer is a blessing for a believer which comes with many benefits and rewards but those who intentionally deny this blessing without a reason will be held to account by their Lord. Allah says in the Quran: But there came after them successors who neglected prayer and pursued desire so they are going to meet evil except those who repent and believe and do righteousness and for those will enter Paradise and will not be wronged at all. (Chapter 19 Verse 59 and 60)
NUMBER 3 - KILLING AND MURDER. Killing or murdering any innocent soul is a major sin that can cause a person to enter hell. The Prophet Muhammad (PBUH) said: ''A man will continue to be sound in his religion so long as he does not shed blood which it is forbidden to shed'' Allah says in the Quran: ''And whoever kills a believer intentionally, his recompense is hell to abide therein and the wrath and the curse of Allah are upon him and a great punishment is prepared for him'' ( Chapter 4 Verse 93)
NUMBER 2 - BLACK MAGIC. Witchcraft involves elements of Shirk because it requires worshipping the jinn and seeking the help of the jinn to misguide people and cause misery. Allah has said clearly in the Quran that the one who does black magic will have no share in the Hereafter. Black magic is one of the worst sins a person can commit and is on the same level as Kufr (Leaving Islam) because Allah says many times in the Quran that magic is Kufr.
NUMBER 1 - SHIRK. The greatest of all sins is Shirk (Associating partners with Allah) which leads a person to eternal doom if a person dies in this state. Allah has said in the Quran ''Verily, Whosoever sets up partners in worship with Allah then Allah has forbidden Paradise for him and the fire will be his adobe'' (Chapter 5 Verse 72) in another Verse Allah says ''And indeed it has been revealed to you (O Muhammad), as it was to those (Allah's Messengers) before you: ''If you join others in worship with Allah then surely all your good deeds will be in vain and you will certainly be among the losers'' (Chapter 39 Verse 65)
Although we have mentioned some most of the most severe and deadly sins a person can commit, remember that Allah's mercy is greater than His wrath and He is able to forgive all sins if you repent sincerely and change your ways.
I ask Allah to guide every Muslim to the right path and grant every one of us with Paradise (Ameen)