Question

What are the 3 major sins in Islam

Answer 1

The 3 major sins in Islam are

shirk

Unjustly killing others

magic practice

And these are not only the major sins in Islam, but there are other major sins, including:

consuming Riba 

Escaping and retreating from the battlefield

eating up an orphan's wealth

accusing a chaste women

The evidence for that is the saying of our Noble Prophet in the following hadith:

 : “Avoid the seven destroyers.” They said: “O Allah’s Messenger! And what are they?” He replied: “Committing Shirk with Allah, magic, to kill someone that Allah has prohibited – except for just cause – consuming Riba (Usury), consuming the wealth or property of an orphan, to flee on the day of the march (to battle), and to slander the chaste, unaware, believing women.” (Bukhari)