Ma'rifa is a special knowledge that is acquired through reflective thought, sincere endeavor, using one’s conscience and inquiring into one’s inner world. It is different from (scientific) knowledge (‘ilm). (Scientific) knowledge is acquisition reached through study, investigation, analysis, and synthesis, while ma'rifa is the substance of knowledge attained through reflection, intuition, and inner perception. The opposite of (scientific) knowledge is ignorance, while the opposite of ma'rifa is denial.
Knowledge means comprehending or encompassing something thoroughly, while ma‘rifa means familiarity with or recognition of something—that something may be the Divine Being—in some of its aspects. For this reason, the One of Unity is called the All-Knowing (‘Alim), but He has never been called the One having familiarity with something (‘Arif). In addition, the exacting scholars of truth view ma‘rifa, which also means information, talent, and skill, as the culture acquired by conscience or one’s conscious nature. It has other meanings such as the ability to feel something with the spiritual faculty that humanity has been endowed with, the image of something known in the mind, and the knowledge kept in the memory which gains strength through repetition. From another perspective, it is consciousness, perception, and sufficient information which helps distinguish one thing from another. Ma‘rifa can be summed up as having concise knowledge about something or someone through their acts or works and attributes—knowledge which can be developed and detailed.
In order that one can be among those who have knowledge of God and who are regarded by God as being one of such people, one should have certain theoretical knowledge about God and the ways that lead to Him, recognizing the obstacles on the way, and knowing how to overcome these obstacles. One should also have enough willpower to apply what one knows. One who has true knowledge of God is a perfect human being who knows the Unique One, Who is the Eternally Besought, with His Acts, Names and Attributes, and is a person in whose everyday life this knowledge shows itself. He or she is also one who always keeps the heart purified and pursues sincerity and purity of intention, who can remain free of negative or evil moral qualities as far as possible, overcoming whatever dark emerges from the spirit and threatens to darken one’s horizon, and thereby demonstrating loyalty to the All-Watchful Guardian. Such a one can bear everything that befalls on God’s way to obtain His approval, and invites others to the way of the Prophets, which shows itself through God’s confirmation in every step, and whose lights he or she always feels with pleasure.
There is another approach to ma‘rifa that ma‘rifa is the ability to perceive something as exactly what it is in itself, in its true nature and identity, and based on the thing itself. According to this approach, knowledge of God is knowing the Divine Being with His Essential and Affirmative Attributes beyond all conceptions of modality. This is different from comprehending, perceiving and establishing other things, and is based on perception and knowing by conscience. This knowledge and perception should not be confused with modern intuitionism. The Divine Being is beyond all concepts and cannot be comprehended, perceived or scientifically known, although a certain knowledge or familiarity can be acquired of Him through His Acts, Names and Attributes.
The acknowledgment that The inability to perceive Him is the true perception, excellently expresses the inability of anything limited to perceive Him and the imperceptibility of the One Who is Infinite. The same meaning is exquisitely expressed in the saying, We have not been able to know You as knowing You requires, O the One Known.
It is only God Whose existence is absolute, and the greatest truth is acknowledging His Existence and Oneness. The first step in acquiring knowledge of Him is the attainment of belief, being a Muslim, and excellence—worshipping Him as if seeing Him. In realizing such a blessed aim, one should continue one’s traveling to the True Source of all gifts and blessings without turning to anything else as a source. One should be able to feel a new joy of reunion in every gift and blessing with which one is favored, and as the final point, gain familiarity with the mysteries of His Names and Attributes, and, if possible, of His Being.
This consideration is expressed as follows in Lutfiya by Wahbi:
Try your hardest and be one who has ma'rifa of Him,
One favored with knowledge of Him!
For the All-Loving declared, “so that I may be known;” 
Knowing God is the ultimate cause for the creation of the two worlds;
and knowing God is the adornment of humanity.
Those devoid of knowledge of Him are low in rank.
Knowing Him is a spiritual kingdom,
and Knowing Him is a Divine gift and blessing.
When you, O moving spirit, receive this gift and blessing;
the two worlds will be yours.
The following words, which are narrated in books concerning Sufism as a hadith qudsi—a saying, the meaning of which is from God and the wording of which was inspired in the Messenger—are the gist or kernel of all explanations concerning knowledge of God:
O humankind! One who knows his self also knows Me; one who knows Me seeks Me, and one who seeks Me certainly finds Me. One who finds Me attains all his aspirations and expectations, and prefers none over Me. O humankind! Be humble that you can have knowledge of Me; accustom yourself to hunger so that you can see Me; be sincere in your devotion to Me so that you can reach Me. O humankind! I am the Lord; one who knows his self also knows Me; one who renounces his self finds Me. In order to know Me, renounce your own self. A heart which has not flourished and been perfected through knowledge of Me is blind.
Knowledge of God sometimes becomes a source of wonder and astonishment for initiates, as has been said, “One who knows the Ultimate Truth becomes dumbfounded and tongue-tied.” But it sometimes becomes a means of expression for them, as has been said, “One who knows the Ultimate Truth finds his voice.” The voice finds its overflowing expression in one’s excitement and speech and echoes in many other ears. Although opposites, both the saying of Muhammad Parisa,  “There is none who knows the Divine Being other than Himself,” and the saying, “I know none else save God,” are true each in its own context.
There is none other than Him who has a true, substantial existence, and there are no true acts other than those done by Him. Other beings have a relative existence when compared with Him, and other acts, which take place in the cycle of causality, is of a relative nature. For this reason, knowledge of God is when an initiate melts away in the light of the Ultimate Truth and gains a new, “true” existence. This may be viewed as self-annihilation in God and subsistence by Him. I think the author of al-Minhaj stresses this fact in these verses:
If you can see with the lights of certainty,
then do not see one who knows and the One Known differently.
Fuduli  expresses this depth of knowledge of God as follows:
One who knows God is not one who knows
the wisdom of the world with what is in it.
One who knows God is he who does not know
what the world is with what is in it.
Sufis have made other descriptions concerning knowledge of God. According to these descriptions, knowledge of God is knowing the truths of the Divine Names and Attributes, grasping the phenomenon of the manifestations in existence and the discovery of the existential mystery, deeply perceiving the truth of existence with its originality and shadows, and understanding and representing in life the truth of religion according to the Will of the All-Desired One, Who is the final goal of those who set out to reach Him. Each of these descriptions requires a voluminous work to explain and is therefore beyond the scope of this study. We will only cite here some verses from Diyaiya (“The Book of Light”) which point to some dimensions of the subject matter:
The third chapter is about knowledge of God, O valiant young one;
to describe it the wheel of speech is unable to work.
There is no scribe nor a pen to write about it;
one cannot get his tongue around it to express it.
The mirror of reason is veiled from understanding it;
the ability of perception has nothing to say in it.
Only the bird of imagination can fly toward it;
there is no example that we can coin to explain it.
Here the gift comes only from God;
this is a light-diffusing, sacred rank.
The whole of creation is immersed in this realm,
which is more spacious than all the worlds.
There is no true existent save He Who is the One,
perceiving this is the real vision.
Do not interpret this vision in another way, or else,
it will mean unbelief and heresy, O one with body of light.
It is not the eyes in the head which have this vision;
The All-Loving One is all-free from vision by these eyes.
The innermost faculty—secret—discerns this truth,
when you find this faculty in you, you can understand it.
Human scientific knowledge and perception have nothing to say;
the merit is in wonder and helplessness in this field.
Perception of one’s helplessness is perception of the Ultimate Truth;
listen to what Abu Bakr, the truthful one, says concerning it. 
The rank of knowledge of God (ma‘rifa) is a rank of wonder, utter astonishment, and awe. It is possible to see this in almost all the reflections of the scholars of Sufism on knowledge of God. Some of them see it in direct proportion to the excess of the feeling of awe and have concluded that the deeper one is in knowledge of God, the deeper one’s feeling of awe is. Others regard knowledge of God as being the base of serenity and peacefulness and emphasize that inner peace and self-possession increase in proportion to the depth of knowledge of God. Still others consider knowledge of God as the heart’s attainment of friendship with God and the initiate’s following a way to nearness to God.
The approach of ash-Shibli opens new windows on the knowledge of God. According to him, it means that an initiate has an essential relation with none save God, making no complaints when burning with His love, is a sincere, obedient and faithful servant of God who avoids any claims of superiority, and one who worries about his or her end. A person with true knowledge of God and who has a strong connection with the sources of this knowledge, one who has taken refuge in the guidance of the spirit and meaning of Prophethood, and who has built sound relations with the truths that lie beyond human horizons, cannot feel any essential interest in transitory things nor does lower him or herself to feel attachment to others than the Lord. The Qur’an alludes to this highest point in (35:28), Of all His servants, only those possessed of true knowledge stand in awe of God, reminding the traveler of the relation between knowledge and awe or reverence of God. The greatest of those who have knowledge of God, upon him be peace and blessings, said concerning the same point: I am greater than you in knowledge of God, and more intense in fearing Him.
In the books on Sufism, in which the intellect guided by Revelation is operative, and which contain numerous gems of wisdom concerning the “garment of piety” of those who have true knowledge of God, with Whom their hearts are deeply connected, we can find many gems concerning knowledge of God. The following are only a few of them:
The following points which differentiate those who have a sound knowledge of God from others are important. The former have no selfish expectations from whatever good they do, never think of competition for either material or spiritual ranks nor feel jealous of anybody. They do not see themselves as being greater than anyone else, nor do they moan because of missed opportunities, anymore than they feel arrogant because of their accomplishments. Even if they were granted the kingdom of the Prophet Solomon, they would only seek God’s company, regarding it as futile to turn to other things. They feel no relation with beings other than the Almighty with respect to their worldly existence and corporeal selves, and know that one moment of God’s friendship is worth the entire world. They consider being with God among people as a victory that has been granted to their willpower, and see the Divine Will reflected in the face of their determination, recognizing the help of the Lord in the result of their endeavor, alongside many other instances of wisdom and God’s extraordinary gifts. They observe the manifestations of the Divine Oneness in the multiplicity of the creation, and thereby they grasp how a drop is transformed into an ocean, and a particle into the sun. They witness in their conscience how nothingness or non-existence is a fertile land, to be planted with existence and live drowned in ecstasies and intoxication.
Self-possession, steadfastness, seriousness, profundity, and resolution are the clearest and most important signs of perfect knowledge of God. Those who have this degree of knowledge live under the shower of the manifestations of God’s friendship and company. No sign of any flaws can be seen in their inner or outer world, nor is any laxity witnessed in their behaviors. They never show impertinence or conceit, even when favored with the most abundant gifts. On the contrary, they always act in a self-possessed manner, trying to lead a self-disciplined, spiritual life.
Obviously, everyone cannot have the same degree of knowledge of God. Some travel on the horizon of perceiving the Attributes essential to the Divine Being and the favors that accompany His Acts. They observe and avail themselves of His proofs that are found within themselves and in the outer world, with the result that their love of truth and their relation with the Greatest of Truths are witnessed in their manners. They travel between the Divine Acts, Names and Attributes and are thrilled with the different melodies of belief, knowledge of God, love, attraction and the feeling of being attracted by God to Himself. They feel in their conscience the reflections of the Divine Acts or operations in the universe and pursue more and more the pleasure entailed in observing ever new colors and aspects. This is a way bequeathed by the Prophets and it is a way that can be followed by everyone. One who travels along this way of objective truth travels toward the Ultimate Truth under the arches of His regard and compliments.
On this path there are others who feel all the dimensions in existence ending in one dimension, who feel that everything is annihilated in God. It is as if they have reached a point where the lights and manifestations of the Divine Being and Attributes come together from the perspective of humanity and annihilate their very being in the Divine Being, attaining a new existence with the Self-Subsistence of Him Who is the All-Knowing and the Ever-Existent.
While those belonging to the former group travel in the realm of the Divine Attributes and Qualities, others have already directed themselves to the Source of these Attributes and Qualities. Therefore, their observations and sensations are not aimed at either the Attributes exclusively in such a way as to veil the Being in their minds or spirits, nor at the Being exclusively in such a way as to suggest the denial of the Attributes. For this reason, such an approach has been regarded as the way of the perfected and most advanced, and the main path that is followed by those who travel to the greatest nearness to God.
The Book, the Sunna, reason, and the Divine system in creation and human primordial nature bear witness to the truth of this way along which God’s works of Art show themselves brightly. Initiates who have firmly established their feet on this path witness at every step that God witnesses His Existence and Oneness, and they cannot help but utter, God bears witness that surely there is no deity but He (3:18). They hear in their conscience the confirmations of angels and those possessed of knowledge as a reflection of God’s Own witnessing, and continue to utter: and the angels and those possessed of knowledge (also bear witness to the same truth) (3:18). Then, they see that all means and causes that are not essential to His Being having vanished, and they are able to be at perfect rest and to find perfect peace.
There are others who have such abundant knowledge of God that proofs of God are no longer needed in their world; all the things that witness Him are humbled in the face of their being in the Presence of the True Witness; all the means tremble with the shame of making distant whatever is near, and all the heralds are silent and busy with correcting the words that they have uttered. At this point, where everything is seen by the conscious nature as witnessing Him beyond all concepts of modality, the eyes are dazzled by the brightest manifestations of the “Divine Facial Light,” and all other identities save His are lost. Those who have reached this point see that the True Source of existence and knowledge surrounds everything from all sides, tasting the pleasure of perceiving every being’s perception of Him according to their level, and feeling that everything is annihilated in Him. They sense the way in which the manifestations of the Divine Names are combined with those of the Being, Attributes and Acts. The conscience is saved from any feeling of dependence on causality and reaches the horizon of Surely we belong to God (as His creatures and servants), and surely to Him we are bound to return (2:156). But this never means, as some have assumed, “absolute annihilation” or “union with God.”
Our Lord! Grant us from Your Presence a special mercy and arrange for us in our affairs what is right and for our good! And bestow blessings and peace on our master Muhammad, by whom the mysteries came to light and the lights shone brightly, and on his pure Family and Companions.