Perhaps we should say that retributions are also a manifestation of affectionate sentiments and love. In du`as (supplication to God) we read: "ya man sabaqat rahmatuh ghadabah" - "Oh You in whom mercy and love have taken precedence over anger", i.e., because You want to be merciful You are angry; otherwise, if that mercy and love did not exist, neither would the anger.
It is like a father who becomes angry with his son because he loves him and is concerned for his future. If his son opposes him, he becomes angry, and he may sometimes beat him, but despite however much ruder behaviour he may see from others' sons and children, he never gets worked up by it. In the case of his own son he becomes angry, because he has affection for him; but in the case of others, he does not become angry, for he has no affection.
On the other hand, affections sometimes deceive; that is to say, there are sentiments which the intellect cannot truly understand, as the Qur'an says: In the matter of God's religion (i.e., the divine laws) let no tenderness for them (the offenders) seize you (an-Nur, 24:2). The reason for this is that Islam, while it demonstrates concern and affection for individuals, is also concerned about society.
The greatest sin is a sin which appears small in the eyes of man and seems to be of no importance. Amir al-mu'minin said: The most serious sin is the sin which the sinner imagines to be slight and insignificant. (Nahju 'l-balaghah, Saying no. 340).
The spread of sin is something which hides the seriousness of the sin from people's sights, and makes it seem nothing in the eyes of the individual.