Imam explains the matter through his theological works as following:
When the Prophet reviews your deeds and he sees how many errors and sins there are, how upset and distressed will he be?
You do not want the Apostle of God to become upset and distressed; you do not want to break his heart and make him sad.
When he witnesses that the page of your deeds is replete with backbiting, slander and speaking ill of other Muslims and that all your attention was devoted to this worldly and materialistic affairs and that your heart was overflowing with malice, hatred, spite, and suspicion towards each other, it is possible that in the presence of God, the Supreme and Holy, and the angels of Allah, he will be embarrassed that his community and followers were ungrateful for their divine blessings.
And thus unbridled and heedless they betrayed the trust of God, the Holy and Supreme.
Someone who is related to us, even if in a menial position, if he errs, we become embarrassed.
You are related to the Apostle of Allah, may the peace and blessings of Allah be with him and his progeny; by entering the seminary, you have related yourself to the Law of Islam, the most Noble Apostle and the Noble Qur’an.
If you perform ugly deeds, it upsets the Prophet and he cannot bear it, and God forbid, you may be damned.
Do not let the Apostle of Allah, peace be upon him and his progeny, and the pure Imams become upset and saddened. The heart of man is like a mirror, clear and bright, and because of too much attention of this world and too many sins, it becomes dark. However, if a person at least performs the fast for God, Imam Khomeini further explained.
The Almighty, sincerely and without duplicity (I am not saying that other acts of worship are not to be pure; it is necessary for all of the acts of worship to be performed sincerely and without duplicity), then this worship which is a turning away from lust, putting aside pleasure, and cutting oneself off from all but God, if it is performed well in this single month, perhaps the grace of God will be extended to him and the mirror of his heart will be cleaned of its blackness and tarnish.
And there is hope that he will change his ways and become dissuaded from this wilderness and worldly pleasures.
Read more articles:
Imam Khomeini stresses that impeccability [ismat] is perfect faith