dontconvert2islam invokes a powerful concept; Islamic scales of justice?

In answer to the video "Worst Creatures in Islam"

In continuation to the earlier discourse about judgement in the hereafter. In the case of those who rejected or disregarded most or all of the directives of the Quran when it was communicated to them (Muslims and non-Muslims alike) and who transgressed willingly and rebelliously, then despite their good actions, their measurements will be light

23:102-103"Then as for him whose scales/mawazin are heavy, these are the successful. And as for him whose scales are light, these are they who shall have lost their souls, abiding in hell".

The Quran also clearly says that among the Muslims themselves there are different grades in God's eyes 35:32-5 and although all will eventually enter heaven, this entry will be granted differently from person to person following a personalized appropriate trial, going from short and easy to lengthy and difficult. Some will even have to pass through Hell as long as Allah deems fit before being granted entry in heaven 6:128,11:106-108 and the Quran has mentioned several crimes such as murder, corruption of inheritance, abusing the weak people's wealth or charity etc whose perpetrators will go to hell regardless of their faith. It is in such context that the following prophetic saying is understood

"Gabriel, upon him be peace, came to me with the good news that anyone from my nation who dies without associating partners with Allah will enter Paradise. I said, “Even if he commits adultery and theft?” The Prophet said: Even if he commits adultery and theft".

Elsewhere

"People among those who worshiped Allah alone (ahl al-tawh?i¯d) will be punished in the Hellfire until they are coals. Then the mercy of Allah will reach them and they will be taken out and presented at the gates of Paradise. The people of Paradise will pour water over them and they will grow just as the stubble carried by the stream grows, then they will enter Paradise".

These Mawazin/scales of the day of judgement, is in the plural because it isnt the concept of a regular scale that is meant here. The plural indicates that there will be many criteria of evaluation and measurements to which the deeds will be compared, meaning that the good nature of the deed itself is not enough for it to be weighty in the spiritual realm. In fact -as explained in details above- a good deed, even done by someone who has professed Islam, such as prayers, fasts, zakat and others can be rendered null and void in the Hereafter if not done as prescribed by God, Who does not judge actions and deeds according to their external form but on the basis of the faith and sincerity underlying them

2:264,3:117,13:22,33:19,67:2"He is the Lord who created death and life so that He may test you that which of you is better in deed".

The ultimate reality of creation is to be a test in the performance of good deeds rather than the quantity of such deeds. For instance when concluding the passage ordaining fasting upon those claiming to adhere to correct faith, it states

2:185"and exalt Allah for His having guided you, and that perhaps you might be grateful (to Him)".

The bestowal of guidance upon a fasting believer is a conclusive reality however sincerity in obedience is conditional upon the person's level of God-consciousness, hence the term "perhaps" attached to the deeper appreciation of the practice.

In many ways does the Quran explain the fact that quantity isnt what is asked from us but rather quality of deeds, including through subtle and eloquent linguistic devices. 

In 20:75 for example the adjective alsalihat/the good, refers to the deeds, which is rhetorically omitted to bring more focus on the adjective, in this case quality/goodness. Then the verse proceeds to negate quantity and focus on quality, from another angle. The adjective salihat should normally be in the singular feminine, to indicate plural yet the plural feminine is used. This abnormal construction was used even in preislamic literature to indicate that a lesser plural in terms of quantity is meant. Once more, the normal grammatical rule is that a singular feminine adjective comes with an object (the deeds in this particular case) to indicate quantity but if the adjective is in the plural feminine it implies a lesser quantity. Then again towards the verse's end, the adjective alulaa/the high, describing the ranks of the successful in the Hereafter, follows the same abnormal grammatical construction in order to indicate a lesser plural. This implies that the high dwelling places are restricted, few, exclusive, yet even so, in order to achieve these exalted places one doesn't need to exert himself quantitatively but qualitatively as indicated in the first part of the verse. That concept is exemplified in the previous verses, through the account of Pharaoh's magicians who, towards their life's end, came to believe and remain steadfast in their faith despite the promised torture. Elsewhere when it adjoins the salihat to correct faith as a prerequisite for success in the Hereafter, it precedes the word with min/of to indicate that complete accomplishment of all righteous deeds is not the intent, even acting upon a part of the prescribed deeds is enough to be counted among the successful 21:94 and God will never let go to waste even the tiniest of those deeds, done in the most secret of ways 99:7. It is reported that 

"by his good character a man can reach the degree of the one who stands in prayer at night and the one who is thirsty from fasting in the heat of the day".

And as a matter of fact, quality inevitably leads to quantity, eagerness to re-live a spiritually fulfilling experience. Following with the same idea of quality over quantity in terms of deeds is the very general and unspecific injunction to do, side by side with the performance of prayer and charity, any type of good 2:110.  The overall principle in Islam in relations to reward in the afterlife is that nothing we can do in itself merits the disproportionate good that lies in store. Only by God's grace are the righteous believers rewarded with paradise. Thus the Quran and the traditions emphasize moderation in religion, as well as the quality, sincerity and constancy in doing good deeds 

"The Prophet was asked, "What deeds are loved most by Allah?" He said, "The most regular constant deeds even though they may be few." He added, 'Don't take upon yourselves, except the deeds which are within your ability".

  "The Prophet said, "Do good deeds properly, sincerely and moderately, and receive good news because one's good deeds will not make him enter Paradise." They asked, "Even you, O Allah's Messenger?" He said, "Even I, unless and until Allah bestows His pardon and Mercy on me".