Icon painting appeared not as art for art's sake, but for the Church. Thus, its content was determined directly by the needs and the purposes of the Church. These purposes were not material but spiritual. The content of icon painting was interwoven with the life, the evolution, and the whole tradition of the Church, so much so that a knowledge of this tradition will be incomplete without a knowledge and understanding of icon painting.

The faith of the Church in the reality beyond this world, that is, in the truth of the spiritual world, defined from the beginning the content and character of icon painting. The Church was primarily interested in the beauty of this spiritual world and, with the means it possessed, it tried to interpret that world. The Church's transcendental content was not the physically beautiful or the naturally good; for this reason it did not try to depict the natural good and beauty. The purpose and the ideal of Byzantine icon painting was the expression of the category of holiness, which was not made to appeal to the senses by being physically beautiful. In Christian Orthodox art the beautiful is not determined by the natural form of the objects, but by its sublime content, that is, by its power to serve the ideals of the faith. According to St. John Chrysostom, "Thus, we say that each vessel, animal, and plant is good, not because of its form or color, but because of the service it renders." Byzantine icon painting did not copy nature nor seek the form or the color as an end, but taking such technical and artistic elements as were necessary for the believers to become familiar with its spirit, succeeded, through an exceptional abstraction, in rendering the more sublime meanings of Orthodoxy.

These basic ideas of Orthodox icon painting are the main obstacles to our appreciation of icons. When we look at icons, we are struck by their apparent simplicity, by their overemphasized flatness, unreal colors, lack of perspective, and strange proportions. At that moment we should stop and remind ourselves that we are applying to icon painting those aesthetic criteria which allow us to enjoy the works of the Italian masters of the Renaissance. As viewers, we apply the familiar criteria to an unfamiliar artistic expression. A similar misunderstanding occurs when, used to "realistic" representations which shaped our artistic sensitivity, we look for the first time at abstract paintings by Picasso, Kandinsky, or Pollock. We are conditioned by the art of the Renaissance to appreciate the architectural details rendered in mathematical linear perspective, to admire the beauty of the human body, the lush landscapes stretching far towards the horizon, and the still lifes with lights, shadows, and three-dimensional shapes so real that we can almost pick a glass from a table or an apple from a platter. In a word, we are used to see on the surface of a canvas or panel something familiar, easily recognizable, something which we can adequately analyze by using familiar categories of perspective, color scheme, point of view, light and shadow, and volume. Unfortunately, we cannot use this kind of analysis on icon painting because, in contrast to the art of the Renaissance, icon painting is not illusionistic, that is, it does not try to convince the viewer that the world depicted on the panel is real, but, on the contrary, tries to make sure by all the means it possesses, that the represented is unreal, ideal, dematerialized. We cannot diminish the achievements of Byzantine and Russian artists by assuming that they did not know how to paint better. They simply consciously and purposely employed a completely different convention of painting, a completely different artistic language. To be able to appreciate the spiritual depth of icon painting we must learn at least the basic "grammar" of this language.

• Icon painting strikes us by the frontality of the figures. This frontality brings the figures in direct relationship with the viewer and gives the fullest expression to the faces.
• The faces of the saints have large, almond-shaped eyes, enlarged ears, long thin noses, and small mouths. Icon painters attempt to indicate that each sensory organ, having received the Divine Grace, was sanctified and had ceased to be the usual sensory organ of a biological man.
• Icon painting deliberately disregards the principle of natural perspective in order to avoid at any cost the illusion of three-dimensionality. Instead, it gives the impression of complete flatness and the lack of perspective. However, icon painting does use a perspective, called by scholars either reversed or inverted, just to indicate that this perspective is different than the illusionistic perspective of the Italian masters. Inverted perspective depends on multiple points of view. But these multiple points of view are placed in front of the painting, not behind it, which results in background objects often being larger than the foreground ones and in distortions in shapes of some of the objects.
• In addition to the inverted perspective, icon painting uses the so-called psychological perspective which is based on the principle that the most important figure in the composition should be the largest and centrally placed. The viewer's attention is drawn to what is central and larger rather than to what is marginal and small.
• When icon painters depict an event which took place inside, in an interior, they place all the participants in the event outside, indicating in the background the walls of the house, church, palace, or city. This allows them to "uncover" the very essence of the event and give due to the participants instead of having to deal with various interior elements which could obscure the meaning of the events happening inside.
• Since icon painting is not realistic, it shows no natural source of light and does not represent shadows. The only light in icons is the inner light of sacred figures and the divine light of Christ.
• Icon painting has the ability to represent several moments of the same action (story) on one panel. In the scene of the Nativity we can see not only the birth itself, but also the arrival of the Magi, the shepherds spreading the good news, Joseph being tempted by the devil, and even the servant women washing the baby. Some scholars call this the "continuous style."
• Other features of icons which help us in understanding their meaning are simplicity, clarity, measure or restraint, grace, symmetry or balance, appropriateness, and symbolic colors.