Caspar David Friedrich infuses ideas about God into all of his works, some more subtly than others. His view of God is the epitome of the Romantic ideal, and this carries through in his paintings. Some very basic religious ideas are the foundation for his complex, expertly-executed works.
Friedrich felt that God could be understood through nature - pure, unabused nature, untainted by man. He also felt that one could understand and appreciate God best through nature. His paintings encourage multiple interpretations, and beg the viewer to ask questions of themselves and their ideas about God. Two of his works, Monk by the Sea, of 1810, and Woman by the Window, of 1822, are about direct confrontations between mankind's inquisitive nature and God. In the former, a monk contemplates the turbulent sky and ocean before him, while in the latter, a young girl peers out into a misty, veiled sky. Friedrich intentionally didn't answer the questions that the figures have in the paintings, but rather encouraged the viewer to delve further, in the spirit of the Romantic 'call to action'. This is in direct contrast to Classical formulas, in which everything is clearly identified in a painting. The Romantic view encouraged going back to the source of a subject, namely nature itself, rather than rely completely on long-established but human-made formulas, techniques and rules.
These two paintings, through their inclusion of the contemplative figure, act as explanations for Friedrich's other landscapes. In many of those, such as his paintings of the Watzmann mountains, there are no figures, and the viewer is the one who is encouraged to ponder the questions about God suggested by the beauty and mystery of the painting. Drifting Clouds of 1823 is a good example of this. It uses a common Romantic device - mist. The mist and clouds become a metaphor for the veiled mysteries of God. The vague, blurry sky lets the viewers fill in the details for themselves. This is the same cloudy sky that the girl is contemplating in Woman by the Window. In that work and Monk by the Sea, the figure acts out the role of the viewer to help clarify the artist's Romantic intentions.
The figures in those two works also suggest God in another way: through their insignificance, God's importance and power is magnified. The monk by the sea is so tiny as to be barely visible against the expanse of the sky. And the girl by the window, while larger, does not confront the viewer but stares into the sky, drawing the viewer's attention there. She is actively confronting God. Even though the man-made building fills much of that painting, the importance is placed on the far-away sky. Friedrich seems to be saying that no matter the size of man's accomplishments, they pale before the import and mysteries of God. This theme runs through his works, especially in his choice of subject matter. By rejecting not only techniques of Classicism but also the Classical necessity of placing human stories within a work, he allowed nature to exist as a subject for painting by itself. He also streamlined ideas of God, eliminating what he sees as peripheral, human details and placing the religious emphasis of his paintings on pure ideas and questions derived directly from nature. Friedrich's Romantic concepts encourage the viewer to share his views by confronting and examining nature themselves and forming their own questions about God.