What is a Greater Sin?

1) All those sins are Greater which have been specifically termed as Greater in the Holy Qur'an and the traditions. The number of such sins exceeds forty and they all have been explained in the traditions of the Holy Ahlul Bayt (a.s.). The explanation of these traditions will follow later. 

2) All those sins are Greater about which the Qur'an and Hadith explicitly state that those who commit these sins will enter Hell. Or if it is not explicit then it should purport to mean the same. For example the tradition of the Holy Prophet (s.a.w.s.):
"Certainly the Almighty Allah and His messenger disown such a person who willfully neglects prayers." 

In this tradition the punishment of Hell is not named specifically but it amounts to the same thing. Another report corroborates this assertion. Imam Muhammad Baqir (a.s.) and Imam Ja'far as-Sadiq (a.s.) said,
"All those sins are Greater (the doer of which) is promised the fire (Hell)."

There is another tradition from Imam Zadeh Abdul Azeem Hasani, which shall be quoted later. Thus we understand that there is no difference whether the promise of the Divine punishment is given in the Qur'an or in a hadith. 

3) Any sin, which is clearly Greater than a sin specified as a Greater one in the Qur'an and hadith; is also Greater. For example the killing of a person is a sin and it is clear from the Qur'an and hadith. Thus the tradition from Ibne Mahboob clearly states that the killing of a 'soul' is a Greater sin. The Qur'an has promised Divine punishment for murder. Then if any other sin is proved to be more than the killing of a person, by the verses of Qur'an or authentic reports then this sin will also be considered as a Greater sin. For example the Holy Qur'an says that to spread corruption in the world is worse than murder:
"And the (spreading of) mischief is Greater than murder."

Hence we can conclude that the spreading of disturbance must also be counted among the Greater Sins. 

4) Any sin which has all along been regarded as a Greater one by the scholars and the jurists should also be considered as 'Greater'. But it should be ascertained that such a sin has been regarded as Greater from the present time right upto the time of the Masoomeen (a.s.). Examples of these types of sins are to descerate the Holy Ka'ba, or a mosque or to throw away a copy of the Qur'an. All such acts have been regarded as the Greater Sins. Now we shall mention the traditions that explain the Greater Sins.