Wajhullah is the countenance by which God appears before his creatures with and they look to and consider when wanting to remember Him. So, wajhullah is His noble qualities such as life, knowledge, power, hearing and seeing and also every quality from His qualities of action such as creation, providing, forgiveness and mercy, in addition to all of His signs. In Shia ahadith the infallible Imams (as) have been recognized as the greatest examples of wajhullah; because they are the complete and absolute reflection of Allah’s names and qualities and Imam Ali (as) is named wajhullah for he is the complete reflection of Allah’s names and qualities.
Consequently, when being the complete manifestation of Allah’s names and qualities, similar to Allah’s holy essence, they won’t perish. Therefore, although we cannot see and witness the presence of Imam Ali in terms of his material and physical being, he is always present. Moreover, the last Imam, Imam Mahdi (as) is the continuance of that same one light and is considered to be wajhullah also, that is present in this world.
The definition of wajh (countenance):
The two words “wajh” and “jihah” mean the same thing. The wajh of something refers to the part that stands before others and has some kind of relation with them, just as how the wajh of any physical object is its exterior, and the wajh of a human is the part that which he faces people with.
Wajhullah refers to the noble qualities of Allah such as life, knowledge, power, hearing and seeing and including His qualities of action, namely creation, providing, forgiveness and mercy, in addition to all of His signs.
What is meant by “وجه الله” in the holy verse?
There are two interpretations for “وجه الله” in the ayah “کلّ شیء هالک إلا وجهه” proposed by the interpreters of the Holy Quran:
1. Some interpreters maintain that what appears to be meant by “وجه (wajh)” is God’s essence, meaning that everything will perish except for God’s essence. Based on this perspective, the ayah is irrelevant to the mentioned question.
2. Others believe that “وجه (wajh)” is anything that is somehow associated with Allah; His names, qualities and religion, the good deeds of His pious servants, those servants that are close to him, such as the prophets, angels, martyrs and believers whom His mercy has encompassed; all are examples of wajhullah.
Based on this interpretation, every creature we can imagine is considered to be mortal and temporary and there is no reality and true substance to their being except for the aspects that God has blessed them with and whatever isn’t connected to Allah definitely has no true substance. It is simply an illusion or a mirage our imagination has given reality to. Similar to an idol that whose true substance is wood and stone or metal, or like the human being which God has created with two facets, the body and soul and his qualities, all and all are originated from Allah. Therefore, our share of reality is what God has generously granted us with and this blessing is one of His signs that show His noble qualities such as, mercy, provision, generosity, goodness etc. Hence the reality that always exists and never perishes is God’s noble qualities and His signs because of His essence. Of course, what is meant by the perishing of all but wajhullah, is that all will undergo change and reach a higher level of existence, not that everything will turn to nothingness, rather it is a transition from this world to the next and the hereafter.
In any case, according to these two interpretations the meaning of the ayah is: everything other than God Almighty is mumkin al-wujud (contingent existence) and has been given existence by God, hence, in and of itself it has no existence; the only being that never perishes is God’s essence. 
Now if one accepts the second interpretation, who will the examples of wajhullah be?
Who are the wajhullah?
Generally, everything that somehow relates to the divine and possesses a divine facet – just like how we said in the second interpretation – is wajhullah; the Holy Quran states: “And the East and the West are Allah's, therefore, whither you turn, thither is Allah's purpose; surely Allah is amplegiving knowing”. Everywhere we glimpse, there is wajhullah; for His knowledge and power encompasses everything; as Imam Ali (as) says: “Praise is worthy of thy God that has manifested for His creations by creation.” Therefore, the vast portrait of this world is the reflection and display of Him. Since man is one of His creations and His successor in this world – “And when your Lord said to the angels, I am going to place in the earth a khalif (representative) – he possesses the highest and most noble rank and position among all of Allah’s creations. Now, when God as the true owner of this world has the greatest position His successor definitely carries the greatness and holiness of His names and qualities in being wajhullah and this greatness is instilled in every human being.
Then again, the complete man is the absolute reflection of Allah’s jamal (beauty) and jalal (majesty) qualities that is entitled to Allah’s names and qualities more than any other creature which makes his sayings, actions, writings, silence and every aspect of his life reminiscent of God Almighty. Thus, the complete man is wajhullah a’zam (the great wajhullah) among other creatures. Given the ahadith, we realize that the messenger of Allah (saw), Imam Ali (as), Hadhrat Fatima (sa) and the other Imams (as) consist of unique and special positions which are the true manifestations of the complete man and wajhullah which hold a great existential position in the world; for they are the manifestation of “the great name of Allah”.
Then again, Imam Ali (as) has fulfilled the duty and role of being God’s creation in the best manner possible and Allah’s names have completely inspired his being and he is (as) is the great name of Allah. The isme a’zam (the great name) is a rank unreachable for others, one with such a blessing can interfere in the affairs of this world and do supernatural things. And this is what is meant by Imam Ali (as) and the other Imams (as) being wajhullah.
In many hadiths we can see that the prophets and infallible Imams (as) are considered to be wajhullah:
1. Imam Reza (as) told Abassilah: “…the wajhullah are the prophets and messengers by which the people remember Allah Almighty and His religion with. God Almighty has said: “کُلُّ شَیْءٍ هالِکٌ إِلَّا وَجْهَهُ”.
2. In line with the ayah, Imam Sadeq (as) has stated that: “We are the Wajhullah through which you are guided to Allah”.
Thus, due to the fact that Imam Ali (as) – along with the other Infallible Imams (as) whose origin is all from the same light - is the paradigm of Allah’s names and qualities do not perish and although we don’t witness them in a physical form in this world, their souls are eternal and immortal.
What is meant by Imam Ali being wajhullah is that his holiness is the manifestation and complete reflection of Allah’s names and qualities and Allah’s great name. Although we don’t witness him in a physical form in this world, his spiritual entity and wajhullah form is, similar to Allah’s entity, eternal and imperishable.
For more information, please refer to Question 7236 (site: 7354) (Reasons as to how the prophet and the Ahlul-Bayt are alive).
 Tabatabai, Muhammad Husein, Tafsir al-Mizan, Farsi translation by Musavi Hamedani, Seyed Muhammad Baqir, vol. 16, pg. 134, Islamic Publications Office, Qom, fifth print, 1374 (solar calendar); Qurashi, Seyed Ali Akbar, Qamuse Quran, vol.7, pg. 184, Dar al-Kutub al-Islamiyyah, Tehran, sixth print, 1371 solar calendar.
 Farsi translation of Tafsir al-Mizan, vol. 16, pg. 134.
 Makarem Shirazi, Naser, Tafsir Nemouneh, vol. 16, pg. 189, Dar al-Kutub al-Islamiyyah, Tehran, first print, 1374 solar calendar; Tabarsi, Fadl bin Hasan, Majma’ al-Bayan fi Tafsir al-Quran, translators, vol. 18, pg. 246, Farahani Publications, Tehran, first print, 1360 solar calendar.
 Farsi translation of Tafsir al-Mizan, vol.7, pg. 144 and vol. 16, pg. 134.
 Of course, although the idol worshippers associate the idols with Allah, and admit that their (the idols) existence comes from Allah and his wajh, but they see the idols as independent in intervention and management and don’t associate it with Allah’s intervention and management, and that is why they would worship them instead of Allah, while the truth is that nothing is independent in any affect, making Allah (swt) the only thing worthy of worship in all of existence. (Farsi translation of Tafsir al-Mizan, vol. 16, pg. 135).
 Ibid, vol. 16, pp. 134-135.
 Ibid, vol. 16, pp. 137-138.
 Ibid, vol. 16, pg. 136.
 Baqarah:115 “وَ لِلَّهِ الْمَشْرِقُ وَ الْمَغْرِبُ فَأَیْنَما تُوَلُّوا فَثَمَّ وَجْهُ اللَّهِ إِنَّ اللَّهَ واسِعٌ عَلیم”.
 Nahjul-Balaghah (Subhi Saleh), pg. 155, Dar al-Hijrah Institute: “الْحَمْدُ للَّهِ الْمُتَجَلّی لِخَلْقِهِ بِخَلْقِه”.
 Baqarah:30 “وَ إِذْ قالَ رَبُّکَ لِلْمَلائِکَةِ إِنِّی جاعِلٌ فِی الْأَرْضِ خَلیفَة”.
 Javadi Amoli, Abdullah, Ali Mazhare Asmaye Husnaye Elahi, compilation: BandAli, Sa’eed, pg. 13, Isra Publications, Qom, first print, 1380 solar calendar.
 Allamah Hasanzadeh Amoli, Hasan, Ensane Kamel az Didgahe Nahjulbalaghah, pp. 58-59, Qiyam Publications, Yaran Print, Qom, third print, 1381 solar calendar; Ali Mazhare Asmaye Husnaye Elahi, pg. 14; Muhammad Shuja’i, Ensan va Khelafate Elahi, pp. 25-38, Institute of Cultural Services of Rasa, Tehran, first print, 1362 solar calendar.
 Majlisi, Muhammad Baqir, Bihar al-Anwar, vol. 4, pg. 3, Tabarsi, Al-Wafa’ Institute, Beirut, Lebanon, 1404 AH.
 Ibid, pg. 5, hadith 10.
 Ibid, vol. 36, pp. 223 and 281: “یَا مُحَمَّدُ إِنِّی خَلَقْتُ عَلِیّاً وَ فَاطِمَةَ وَ الْحَسَنَ وَ الْحُسَیْنَ وَ الْأَئِمَّةَ مِنْ نُورٍ وَاحِد”.
 See: Allamah Hasanzadeh Amoli, Nahj al-Wilayah, pp. 8-14, Alef Laam Mim Publications, Navide Eslami Print, Qom, second print, 1385 solar calendar.